I’ve had this happen since I think late F38 or F39, and it happens on F40. I had it happen about a week ago with openSUSE TW also (I didn’t run into it prior to that and thought this was Fedora-specific).
Intel UHD 630, Xorg or Wayland. I suspected it had to do with audio because sometimes I’d hear my speakers pop on that screen, but disabling onboard audio nor using several USB audio cards fixed it.
When that gray-screen pause happens, on Xorg sessions I can unplug my 3.5mm speakers, plug it back in (to trigger a what device headphones/headset/mic prompt), Win key + L to lock, and recover out of it, but that assumes I have something in 3.5mm (no recovery with just my laptop by itself).