Deluge
Ok, so this worked for me. Feel free to add it to a wiki or something, if you think others will benefit from it. I'm running windows 11 64 bit.
1. Open control panel
2. Open indexing options
3. Click advanced
4. Select the "file types" tab
5. Remove the checkmark for any file you don't want in jump lists/MRUs/search. I did it for .torrent
Now...what threw me off was that there are still items on the start menu and when right clicking the icon on the taskbar. For both of these I had to right click one of the entries and select to remove it from the list. Then the rest of the list disappeared. They came back a couple of times, but I guess that's because windows was still removing it from the search cache. After 10 minutes or so, the effect was permanent. It has survived two reboots.