Homekit mqtt entities not showing up after major update

I just updated Home Assistant and OS (running on Rasp PI4) after one year.

I reconfigured all MQTT entities and they are working fine.
However, they are not showing up in the Home app on my iPhone anymore. Only the lights that are NOT configured as MQTT in the configuration.yaml file, but by just adding them when discovered show up.
When I click on the manually congured mqtt entities in the dashboard and then click the “settings wheel” I get the message " This entity (‘light.kitchen’) does not have a unique ID, therefore its settings cannot be managed from the UI. See the documentation for more detail". Could this have something to do with it?

What am I missing?