Since the update to gnome 40 (i guess, because it was the last big update with many packages) my system instantly wakes up after I set it to suspend. When I first lock my screen then press suspend it works like it should.
I experienced it with Kernel 5.4 and now 5.10.
When it wakes up again after the first “suspend” it does not show the lock screen immediatly, but the last show application on my desktop. After 2-3 seconds the lock screen appears to suspend it finally.