I have a Galaxy Note 10+ and have been getting these Google notifications for the Secure Folder - multiple times a day. I don't even have Google set up in the Secure Folder! Worse, tapping on it, as instructed, does NOTHING but clear the notification and pull up the notification shade. The phone does not enter Secure Folder.
There are only a few apps I have installed in it, other than the mandatory stock apps that Samsung insists on putting in there. The notification returns after an hour or two.
I intend to use the Secure Folder for very specific work purposes: so there aren't a lot of apps I need. Here's what I've done so far:
Installed the June 1, 2020 security patch.
Opened Settings -- Apps -- Show System Apps and wiped cache on everything related to Googleandthe Secure folder.
Booted into recovery and wiped the phone's cache
The ONLY cause I can think of, and I'm guessing here, is that one of the few apps I've installed in the Secure Folder has an update available. Since I can't add Google Play Store to the Secure Folder (Samsung doesn't list it as an available app), I suspect that there's an update available for one of those apps but I can't get an update to it.
For example: the Facebook app is ONLY in my Secure Folder for a reason (not the least of which is their egregious track record handling personal data... so I want the app to have access to as little as possible) - if there's an app update, I think Google is up against a wall with Knox. It's trying to update the app and Knox won't let it. I'm going to try adding it from the Galaxy Store. Hopefully that will take care of that app.
If it's one of the other apps I have in the Secure Folder that isn't available in the Galaxy Store, however, then there's a real problem that SAMSUNG is going to have to resolve.