[Edit: The GitHub repos are called "syncthing-android". The Android apps are called "Syncthing-Fork" or "Syncthing-Fork Wrapper", which adds to the confusion.]
If I recall, there used to be a syncthing-android app on Google PlayStore. That was discontinued by @imsodin in Oct 2024 (https://forum.syncthing.net/t/discontinuing-syncthing-androi...).
There was a version of sycnthing-android on F-Droid. I don't remember who maintained that. I have version 1.30.0.4 installed. But I cannot find any information about that version anymore.
The current version on F-Droid is 2.0.12.1. That seems to be maintained by a fellow named @researchxxl. Apparently @researchxxl claims to have inherited the source code and signing keys from a person named @Catfriend1 (Not sure who that is, the maintainer of version 1.30.0.4?)
There is another fellow named @nel0x who seems to be maintaining a different version of synchthing-android? (Edit: Here it is, https://github.com/nel0x/syncthing-android, which says that it is a fork of the one maintained by @Catfriend1).
When google locked down on file apis a year or so ago, the official syncthing-android pulled out of google play, but syncthing-fork stuck around in fdroid as the fork was for personal purposes, and they were using fdroid for distribution in the first place.
This change in ownership is new to me, but I'm also not surprised it happened as syncthing-fork was always a personal project.