Transmission was stable with no updates for a long time, and a few years back it started adding in more recent bittorrent features.

First update went ok (IIRC), next one had a feature that few users spotted - a bug caused it to hammer tracker servers with update status requests.

The result of that was that many tracker operators started to ban Transmission - the careful ones banned the specific version number, a good many banned either Transmission or the major base release number (4?)

To this day, recent Transmissions version that do "play nice" with trackers are penalised and get fewer to no peers and seeds from a torrents tracker pool.

I still like Transmission for the tight headless mode and remote control aspects .. but maybe two out of ten torrents stall up and I transfer control to a qBitTorrent instance.