I almost rage-quit using Signal when they started that nonsense. I finally relented and entered a PIN (which I’ve forgotten). But it stopped requiring it…
Now I just have about 15% of my screen in Signal showing the “Verify your Signal PIN” UI, which I’ve trained myself to ignore so hard that I almost never even notice it’s there.
The PIN is just one way these platforms leak supposedly secure info. But even without that weakness, Signal and all the rest are a joke in terms of real privacy.