@MarcH1 In my case, I believe the problem stems from the rapid fire of commands from the Google Home automation to the partner services are either getting lost or ignored by the external service.
All of my bulbs (except 1) are Philips Hue and I found that using the Google Home bedtime automation to turn off the bulbs would sometimes (couple of times a week) miss turning off a light or two (Not the same lights each time) until I just decided to (In the hue app) setup a zone with all my lights and a scene to set them as I want them to be at night. I called this scene "Night Mode" and in my bedtime routine I now have only one command to call this scene instead of sending a command for each hue bulb.
I also have the 1 bulb, several nightlights (controlled by smart switches) and other devices that are in setup the Tuya Smart app that I have created a scene for as well.
My routine went from 32 actions down to 2 as I now just call the Hue scene then the Tuya scene. It's been several months since I made this change and I have had no problems since.
If any of your bulbs are Geeni and you are using the Geeni app & service to connect to Google Home, this could be a source of your problems as well. When I used Geeni, several times a week, Google assistant would tell me that it couldn't reach Geeni. I ended up getting rid of the Geeni service and moving the Geeni devices onto the Tuya Smart app which seams to have a much more stable integration with Google Home.
