Has F-Droid ever removed any apps?

Just asking out of curiosity

I’ve just noticed that a game of mine “Ninja Training” is not listed anymore. So yeah.

You are wrong. It is in the archive.
To get it back someone has to fire up the rebuild for it.

You have to activate the Archive Repo to see them.

Apps are removed from time to time for a number of reasons. Occasionally, we realized an app wasn’t free after all. Or there are other reasons. But we mostly try to avoid removing builds. Many builds will be moved to the archive.

For what reasons have they been removed? And even if an app was not free how come they are removed?

f-droid.org aims to distribute only verified free software, so things
that require proprietary blobs should be removed.