Idk if this was the article you were thinking of, but I used this article from torrentfreak and also settled on Mullvad. I've been subscribed for years, they're great and pretty cheap.
Edit: I reread your post and realized that you're looking for a VPN with port forwarding. Frankly, I trust Mullvad enough at this point that if they removed port forwarding as a feature, then I assume that feature is probably just a bad idea for VPNs in general.
can someone ELI5 what this is, exactly? A program to run on your computer that helps out the Internet Archive? How exactly is it helpful for the Internet Archive?