I don’t know if it was always like this or they changed it but Proton Calendar free tier have 3 calendar limit not one. Please update the website page.
Used to be one indeed so that must have changed. Good catch.
Thank you for this update! See Update Proton Calendar information by julianfairfax · Pull Request #2278 · privacyguides/privacyguides.org · GitHub
It’s a very recent thing
Thanks for making the pull request