Firefox’s free VPN will offer 50 gigabytes of monthly data, which is pretty generous for a browser-based VPN. A Mozilla account is required to make use of it, which isn’t a hardship (they’re free), but is a point of friction some may wish to know upfront.
~~ No, Mozilla uses Mullvad as a partner, they’re a serious and nolog VPN provider.
https://mullvad.net/en/blog/mullvad-vpn-was-subject-to-a-search-warrant-customer-data-not-compromised ~~ EDIT: Didn’t read the article, the free VPN won’t be using Mullvad apparently.