@tvvitchy53 Thanks for your feedback and sorry to hear you’re having issues with Tag Manager disconnecting in Site Kit.
What may be happening here based on your description, is you’ve reached the 100 site OAuth limit, as per the below guide:
https://sitekit.withgoogle.com/documentation/getting-started/install/#multiple-sites
This limit is for 100 active connections, meaning it’s normal if you connect any sites any site number 100 for the longest connected site to become disconnected, and so on.
Another possibility, although less likely based on your troubleshooting, is that a common plugin or hosting feature is changing your WordPress SALT keys, thereby impacting your Site Kit connection.
We’d be happy to look into this further for you if this is not related to the 100 site OAuth limit. To do this could I please ask you to open a new support topic and share your?Site Health information?for one of these impacted sites. You can?use this form?to share privately if preferred.?Hope to see you in the forum!