OK, my wifes newly garmin venu sq 2 had a garmin watch bluetooth "driver" update today and after that she could connect to her connect app on her samsung android phone.
In her connect app the watch in was gone! After 1.5 hours I got the sollution (so Garmin you owe me a consult fee of 150 euros!)
For all who have this problem:
1) Go into android apps via system
2) go to connect garmin app
3) goto storage (sorry if this isn't the exact word i'm translating from dutch)
4) there u empty the cache, it's a button below on the screen
5) you have to also remove the data there
6) remove and reinstall the program
7) Reset your garmin watch to factory settings (https://www.youtube.com/watch?v=QWxRQdgmVWs)
now you've got "clean" everything and you have to set it up as tho you've got a new watch. The thing is ... after this ...no Garmin watch for me! My wife is more forgiving!