Mullvad spends a lot on irl marketing. VPN providers are essentially just about trust as they provide essentially the same service, so marketing is hugely important.

Mullvad and IVPN both don't do affiliate links. Proton is the only VPN that I can recommend that does use affiliate link marketing. They also do a lot of sponsorships. Proton really is a great company with great products.

https://www.privacyguides.org/en/vpn/

Proton VPN. They inverst very much in youtube sponsoring and every other twitch streamer is partnering as well.