A few years ago I was torrenting a large collection of games without a VPN. It wasn't subtle at all. My internet connection kept getting slower and slower. I had to repeatedly restart the download for it to finish.

Afterwards my internet was totally busted. I called my ISP to complain. They walked me through some debugging but I could tell it was bullshit. Suddenly my internet started working. After I got off the phone, I got an automated text from the ISP that my internet had been reactivated.

So yeah. They can/will block your internet for downloading stuff. Use a VPN.

Has anyone dealt with this before and should it be a cause for concern?

I once downloaded a 450+ GB torrent at those speeds ... took like half a year.

Traffic shapers can prioritize connections or streams differently, even if they can’t see inside them. Higher priority for quick connections, like interactive web page views, diminished priority for “oops that’s actually a bulk download it seems”.

Downloading how? Maybe the server is just slow.

If they were on to you, you wouldn't know until you either got a letter or someone showed up with a warrant.

Just a connection issue with the seeder/uploader. That happens sometimes on downloads, but it's rare.