As of Home Assistant 2022.12 you are now REQUIRED to change any of your manual MQTT configs in the Configuration YAML file. Any devices that are using Auto Discovery or other automatic integrations are not impacted by this change. I've covered some of the changes and how I edit things in the video linked below. I also included two before and after configs below to see the necessary changes.
Before
light:
- platform: mqtt
name: "Sink Light"
state_topic: "tele/SinkDimmer/STATE"
state_value_template: "{{ value_json.POWER }}"
command_topic: "cmnd/SinkDimmer/POWER"
availability_topic: "tele/SinkDimmer/LWT"
brightness_state_topic: "tele/SinkDimmer/STATE"
brightness_command_topic: "cmnd/SinkDimmer/Dimmer"
brightness_scale: 100
brightness_value_template: "{{ value_json.Dimmer }}"
qos: 2
payload_on: "ON"
payload_off: "OFF"
payload_available: "Online"
payload_not_available: "Offline"