I have a lot of problems with stability using the linuxserver/transmission docker image in my *arr stack. I setup restarting on unhealthy status in docker compose (using the following test command curl --fail http://localhost:9091 || exit 1) but even then, sometimes I just find that my donwloads have stopped and find that the container is not running at all. Do you have an alternative to suggest, which could run in docker compose?
You can also use a custom UI. I recommend VueTorrent.
In fact, using this mod, you can even have Docker download it and keep it up to date. In qBittorrent you just need to change the WebUI location to /vuetorrent.
https://github.com/gabe565/linuxserver-mod-vuetorrent