I made a change to the TRIGGERcmd and TRIGGER command actions which might fix them. The change only takes effect next time people link their accounts. Unfortunately it doesn't happen very often, so only time will tell if it's fixed. In fact for some reason it's never happened to me yet.
I'll be working on this this weekend. Please keep reporting the problem when you see it. If you tell me the exact time it might help.
EDIT: I think I found the root cause and fixed it today, 9/12/2020 at about 12:30pm EST. You might have to re-link one more time, but after that it should stay linked.
Thank you for reporting the problem. After adding logging for this problem I see it was also affecting Alexa users.
@ANDRES-ROJAS, I might be having the same problem you are. I tried creating a Google Assistant routine that flips one of the virtual switches on, but it won't allow me to select the switch now. I'll look into that, but there's another way that does work.
Here's what worked for me:
Open the Home app
Tap the + to create a routine
Tap "Add starter"
Tap "When I say to Google Assistant"
Tap "Add action"
Tap "Try adding your own"
Type "turn on calculator"