Iirc there were some changes to usage reporting (additional data reported), so users were prompted to enable usage reporting again.

IIRC it was due to the new version having a protocol incompatibility with the old version, which means that users needed to upgrade SyncThing on all of their devices simultaneously to keep using it. I can certainly see how that could be a hassle especially when SyncThing is installed via a package manager or in the case of the Android app, where different sources provide different versions.