I dont know what is causing but i tried tons of fixes, i mainly use public torrenting, and sonarr and radarr are doing it.
I added *.arj and arj to the quality profile avoid list without success, and prowlarr is as torrent (i’ve read sometimes it gets confused and uses nzbget)
Or just set a “*.arj” file exclusion in qBitTorrent’s built in blacklist, (Options>Downloads>Excluded File Names) and use Cleanuperr to automatically delete+blocklist+repeat search for the torrent.
Basically, if Cleanuperr detects an “empty” torrent (because every file was excluded when it was grabbed) then it will automatically delete the torrent from your list, blocklist the torrent in your respective *arr client, then retry the search.