Contacts gone after registration for play store and fair phone update

You can install Signal without gargle play, but for some reason it’s not easy to find from their index page.
Incidentally, I came here looking to see if anyone else was having the same problem updating Signal as me right now, with the update notification doing nothing, and I might have to download this directly myself, but it seems to be not the only non-f-droid app that’s not updating properly at the moment.

Also, I had the same problem as you just described back when I installed whatsapp before giving up on it. With this pattern, I wonder if anyone can work out what’s going wrong here…