Coffee-shop VPNs are too often problematic generally, too often providing negligible benefits over iCloud Private Relay or such, and while too often pretending to be something other than poorly-written metadata collection malware.
Some apps and some web services detect VPNs, and will block that access, whether that block due to the risks of metadata collection, or due to malicious activities arising via VPN, or potentially both.
When things get weird, or when troubleshooting, or when networking generally or network-connected apps specifically get funky, remove the “coffee shop” VPN, and test again.
If removing the VPN fails to resolve an issue with a third-party app, and if removing and restarting and reinstalling the app doesn’t resolve the issue with the third-party app, contact the app vendor support.