I suspect it depends a lot on two main factors:

1. The country you live in

and

2. Your ISP

I live in Sweden and have a local ISP. Been both DL:ing and seeding for over a decade without using a vpn and not hearing a peep about it.

Idk what the situation is in Switzerland, hopefully someone who lives there will answer as well.

It's against the law, so there is chance you eventually get caught, if your seeding copyrighted material. I do not know anybody who was caught, but if your naive, you might get in trouble.

I have gotten a few notice alerts over the year and it seems to depend on what you are downloading not how much or how often. If it is a popular TV show or movie they are more likely to get you versus an old movie from the 80s. Given how easy it is to get a VPN and how cheap it is I would not even chance it.