Sad to see so many upvotes for bad information, no. Signal is a special case (it's their choice to disallow any open source client which they did not build) and does not follow the same rules.

KDE Connect is hosted on Gitlab, advertises install from F-Droid and is just as real from F-Droid as it is from the Play Store. Play Protect routinely tries to save me from this other harmful app (their words not mine) called Squawker.

Play Protect trying to incorrectly remove F-Droid apps is nothing new.