Same here. It has been happening regularly to me over the past 6 weeks, with my iPhone XR.
How do we escalate this issue?
Contact Garmin support via phone - https://support.garmin.com/ They will create a case or add you to the current case.
This was posted on the Garmin Connect Web forum. However, everyone seems to be discussing their issues as related to the Garmin Connect Mobile iOS app.
Please see these threads on the GC iOS forum: Garmin connect keeps logging out since last update iOS and Every time I restart my phone I have to Login In and Reconnect Devices
As well as Garmin's support site: Why Do I Need to Keep Signing Into the Garmin Connect App on My Phone?
Having said that, I'm locking this thread. Please go to the iOS forum thread if you would like to continue the discussion. Thanks.