I'm using a Pixel 5 and had issues too. Something about a cURL extension. I don't think it's anything to do with the pixel but fixed it this way.
I held the Tapatalk app icon instead of tapping it to launch the app, went into app info, hit force stop, cleared cache and memory then opened the app. This is the same as deleting the app and reinstalling it.
After that I had issues logging in until I stopped using my email address and used my username instead. Since then it's been fine but I only just got back in an hour or two ago.
Sent from my Pixel 5 using Tapatalk