I’ve testing and I’m pretty confident that removing a user from the whitelist sheet in a Private Pro app will sign them out immediately.
However, it’s hard to say what would happen with a Public with Email app because nothing would stop the user from simply signing into the app again, so there is no immediate need to sign them out. With that said, there is still internal data within glide that is still maintained (such as user specific data and I assume login authentication). Simply removing a row of data from a sheet wouldn’t sign the user out or remove the internal data for that user.
Instead, I would be curious what would happen if you delete the actual internal user data while a user is signed in. I’m not sure what would happen in that case, but I’m pretty confident that only removing a user profile row will not affect a user all that much, other than removing their data and any conditions based on that data.