Currently, Google only allows a single username/password to be logged into their services up to 25 times. This means if you're using one account across 25 instances, then create a 26th and the very first added will stop working properly. The total number of instances includes Google Sheets, Google Drive, Google Calendar, and Google Contacts. This means that if you're using 5 forms and have set up each of those integrations on every one of them, the total number of instances on the Google login would be 20 (5 x 4).
Having more than 25 instances will cause some of the instances to stop working. With Google Drive, this can be seen when folders don't load properly in the integration settings. Google Sheets might not load spreadsheets properly when added.
There are two ways to work around this restriction. One is to isolate what forms in your account need to use the Google integrations and avoid using them on additional forms. The other is to use multiple Google logins to set up Google integrations on your forms.