There never was a controversy about SyncThing, only a bit of drama about the ownership of an unofficial Android client. I’m still using it, but it’s pinned to an older version for now.

The tldr is the official win and nix versions are ok.

The problem is the unofficial android fork.
The original maintainer decided to hand the keys over to someone else, who thought it was a good idea to create a GitHub account with a name stupidly close to the original maintainer. As there is no history with this new maintainer, people are worried about another zx incident where malware is slowly introduced.

I’m building FOSS alternatives from the ground up on top of IPFS. Not quite ready to use, but very promising (on desktop). Building the abstraction needed to do multi-device edits of the same IPNS key was the hardest part, but that work is done and usable for building any app. Might be another year before everything is stable enough to daily drive the storage implementation due to limited bandwidth to work on it, so I won’t share here – find me in the https://windowsappcommunity.com/discord if you’d like to see the work or contribute. If something happens to syncthing or people want a p2p alternative to the personal cloud, I’ll be there!

I use it between PCs (binary, flatpak) and NAS (Docker), but i believe the android fork is still potentially compromised. Haven’t updated the android version since the repo was taken over.

What controversy?

I did use it a couple of years ago extensively, but moved back to the basics later on: Termux and Rsync.