Pausing Gluetun might do that, or it might route the Torrent traffic over the regular network, in which case you might see a blip in the download rate before it goes up again.
Personally I prefere this docker-ized torrent client, since it’s got the VPN built right in, and I don’t need a VPN to do anything other than torrents.
I’ve been looking for something like this for a while. Calibre is great for managing it on a personal machine, but I want something that I can use on the web and then, with a click, send a book to a Kindle or whatever.