Ok finally, due to a friendly user comment following solution was found:
- Google changed the app token access to restrict it to verified apps only
- To fix it as a workaround you need to:
- Go to Android -> Settings -> Apps -> Google Play Services -> Storage and delete the storage of the play service app.
- Open TabShop again, reconnect the Google account
- Click on the Android sign-in notification
- Ignore the verficiaction warning and click on 'advanced'
- Proceed to TabShop app
- Accept the access to your Google Drive and Google Sheets
Now the Google Sheet sync works again.