diff --git a/homeassistant/components/kostal_plenticore/const.py b/homeassistant/components/kostal_plenticore/const.py
index 5cbc1a2af79c54998fd40d1cf983a2fd50034bfe..9f902da7d2f88a65c0cdeaa981d077fccebd8eac 100644
--- a/homeassistant/components/kostal_plenticore/const.py
+++ b/homeassistant/components/kostal_plenticore/const.py
@@ -16,14 +16,11 @@ from homeassistant.const import (
     PERCENTAGE,
     POWER_WATT,
 )
-from homeassistant.util.dt import utc_from_timestamp
 
 DOMAIN = "kostal_plenticore"
 
 ATTR_ENABLED_DEFAULT = "entity_registry_enabled_default"
 
-LAST_RESET_NEVER = utc_from_timestamp(0)
-
 # Defines all entities for process data.
 #
 # Each entry is defined with a tuple of these values:
diff --git a/tests/components/dsmr/test_sensor.py b/tests/components/dsmr/test_sensor.py
index 88e984cea1b043524f299029e9285c27a696a31e..6d40437d87abbc6eaecdbf0e4559f9190aabb515 100644
--- a/tests/components/dsmr/test_sensor.py
+++ b/tests/components/dsmr/test_sensor.py
@@ -14,7 +14,6 @@ from unittest.mock import DEFAULT, MagicMock
 from homeassistant import config_entries
 from homeassistant.components.dsmr.const import DOMAIN
 from homeassistant.components.sensor import (
-    ATTR_LAST_RESET,
     ATTR_STATE_CLASS,
     DOMAIN as SENSOR_DOMAIN,
     STATE_CLASS_MEASUREMENT,
@@ -137,7 +136,6 @@ async def test_default_setup(hass, dsmr_connection_fixture):
     assert power_consumption.state == STATE_UNKNOWN
     assert power_consumption.attributes.get(ATTR_DEVICE_CLASS) == DEVICE_CLASS_POWER
     assert power_consumption.attributes.get(ATTR_ICON) is None
-    assert power_consumption.attributes.get(ATTR_LAST_RESET) is None
     assert power_consumption.attributes.get(ATTR_STATE_CLASS) == STATE_CLASS_MEASUREMENT
     assert power_consumption.attributes.get(ATTR_UNIT_OF_MEASUREMENT) is None
 
@@ -159,7 +157,6 @@ async def test_default_setup(hass, dsmr_connection_fixture):
     assert power_tariff.state == "low"
     assert power_tariff.attributes.get(ATTR_DEVICE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_ICON) == "mdi:flash"
-    assert power_tariff.attributes.get(ATTR_LAST_RESET) is None
     assert power_tariff.attributes.get(ATTR_STATE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_UNIT_OF_MEASUREMENT) == ""
 
@@ -167,7 +164,6 @@ async def test_default_setup(hass, dsmr_connection_fixture):
     gas_consumption = hass.states.get("sensor.gas_consumption")
     assert gas_consumption.state == "745.695"
     assert gas_consumption.attributes.get(ATTR_DEVICE_CLASS) == DEVICE_CLASS_GAS
-    assert gas_consumption.attributes.get(ATTR_LAST_RESET) is None
     assert (
         gas_consumption.attributes.get(ATTR_STATE_CLASS) == STATE_CLASS_TOTAL_INCREASING
     )
@@ -259,7 +255,6 @@ async def test_v4_meter(hass, dsmr_connection_fixture):
     assert power_tariff.state == "low"
     assert power_tariff.attributes.get(ATTR_DEVICE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_ICON) == "mdi:flash"
-    assert power_tariff.attributes.get(ATTR_LAST_RESET) is None
     assert power_tariff.attributes.get(ATTR_STATE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_UNIT_OF_MEASUREMENT) == ""
 
@@ -268,7 +263,6 @@ async def test_v4_meter(hass, dsmr_connection_fixture):
     assert gas_consumption.state == "745.695"
     assert gas_consumption.attributes.get(ATTR_DEVICE_CLASS) == DEVICE_CLASS_GAS
     assert gas_consumption.attributes.get("unit_of_measurement") == VOLUME_CUBIC_METERS
-    assert gas_consumption.attributes.get(ATTR_LAST_RESET) is None
     assert (
         gas_consumption.attributes.get(ATTR_STATE_CLASS) == STATE_CLASS_TOTAL_INCREASING
     )
@@ -331,7 +325,6 @@ async def test_v5_meter(hass, dsmr_connection_fixture):
     assert power_tariff.state == "low"
     assert power_tariff.attributes.get(ATTR_DEVICE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_ICON) == "mdi:flash"
-    assert power_tariff.attributes.get(ATTR_LAST_RESET) is None
     assert power_tariff.attributes.get(ATTR_STATE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_UNIT_OF_MEASUREMENT) == ""
 
@@ -339,7 +332,6 @@ async def test_v5_meter(hass, dsmr_connection_fixture):
     gas_consumption = hass.states.get("sensor.gas_consumption")
     assert gas_consumption.state == "745.695"
     assert gas_consumption.attributes.get(ATTR_DEVICE_CLASS) == DEVICE_CLASS_GAS
-    assert gas_consumption.attributes.get(ATTR_LAST_RESET) is None
     assert (
         gas_consumption.attributes.get(ATTR_STATE_CLASS) == STATE_CLASS_TOTAL_INCREASING
     )
@@ -407,7 +399,6 @@ async def test_luxembourg_meter(hass, dsmr_connection_fixture):
     assert power_tariff.state == "123.456"
     assert power_tariff.attributes.get(ATTR_DEVICE_CLASS) == DEVICE_CLASS_ENERGY
     assert power_tariff.attributes.get(ATTR_ICON) is None
-    assert power_tariff.attributes.get(ATTR_LAST_RESET) is None
     assert power_tariff.attributes.get(ATTR_STATE_CLASS) == STATE_CLASS_TOTAL_INCREASING
     assert (
         power_tariff.attributes.get(ATTR_UNIT_OF_MEASUREMENT) == ENERGY_KILO_WATT_HOUR
@@ -421,7 +412,6 @@ async def test_luxembourg_meter(hass, dsmr_connection_fixture):
     gas_consumption = hass.states.get("sensor.gas_consumption")
     assert gas_consumption.state == "745.695"
     assert gas_consumption.attributes.get(ATTR_DEVICE_CLASS) == DEVICE_CLASS_GAS
-    assert gas_consumption.attributes.get(ATTR_LAST_RESET) is None
     assert (
         gas_consumption.attributes.get(ATTR_STATE_CLASS) == STATE_CLASS_TOTAL_INCREASING
     )
@@ -484,7 +474,6 @@ async def test_belgian_meter(hass, dsmr_connection_fixture):
     assert power_tariff.state == "normal"
     assert power_tariff.attributes.get(ATTR_DEVICE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_ICON) == "mdi:flash"
-    assert power_tariff.attributes.get(ATTR_LAST_RESET) is None
     assert power_tariff.attributes.get(ATTR_STATE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_UNIT_OF_MEASUREMENT) == ""
 
@@ -492,7 +481,6 @@ async def test_belgian_meter(hass, dsmr_connection_fixture):
     gas_consumption = hass.states.get("sensor.gas_consumption")
     assert gas_consumption.state == "745.695"
     assert gas_consumption.attributes.get(ATTR_DEVICE_CLASS) is DEVICE_CLASS_GAS
-    assert gas_consumption.attributes.get(ATTR_LAST_RESET) is None
     assert (
         gas_consumption.attributes.get(ATTR_STATE_CLASS) == STATE_CLASS_TOTAL_INCREASING
     )
@@ -544,7 +532,6 @@ async def test_belgian_meter_low(hass, dsmr_connection_fixture):
     assert power_tariff.state == "low"
     assert power_tariff.attributes.get(ATTR_DEVICE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_ICON) == "mdi:flash"
-    assert power_tariff.attributes.get(ATTR_LAST_RESET) is None
     assert power_tariff.attributes.get(ATTR_STATE_CLASS) is None
     assert power_tariff.attributes.get(ATTR_UNIT_OF_MEASUREMENT) == ""
 
diff --git a/tests/components/mysensors/test_sensor.py b/tests/components/mysensors/test_sensor.py
index 18d88a24206d61687a26ba14f1824e81a5b4fc6a..d648aebdefd13eccb17d0c6a77566575625b5470 100644
--- a/tests/components/mysensors/test_sensor.py
+++ b/tests/components/mysensors/test_sensor.py
@@ -7,7 +7,6 @@ from mysensors.sensor import Sensor
 import pytest
 
 from homeassistant.components.sensor import (
-    ATTR_LAST_RESET,
     ATTR_STATE_CLASS,
     STATE_CLASS_MEASUREMENT,
     STATE_CLASS_TOTAL_INCREASING,
@@ -75,7 +74,6 @@ async def test_power_sensor(
     assert state.attributes[ATTR_DEVICE_CLASS] == DEVICE_CLASS_POWER
     assert state.attributes[ATTR_UNIT_OF_MEASUREMENT] == POWER_WATT
     assert state.attributes[ATTR_STATE_CLASS] == STATE_CLASS_MEASUREMENT
-    assert ATTR_LAST_RESET not in state.attributes
 
 
 async def test_energy_sensor(