Yes I just did, in a private window, and all I needed to do was complete a captcha.
But even if your IP is on their naughty list, you can delete that data once you have registered, and I would be very surprised if Proton secretly kept it after you delete it.
But even if your IP is on their naughty list, you can delete that data once you have registered, and I would be very surprised if Proton secretly kept it after you delete it.