I also use that, and it's just all over the place.
I've had issues with my carrier, so I just used foreign SIM in roaming for a while. €11 for 40GB is not that bad.

And then I found I can't purchase a train ticket. For some reason, ZSSK (Slovakian passenger railway company) blocked IPs of Lifecell (Ukrainian MNO), but was fine with IP from RackNerd (Virginia).

Oh, and the university I am at blocks IPs from "3rd world countries", the result of which was that Asburn, Virginia is fine, but somehow New York is a 3rd world country.
Their instructions say to use any EU-based VPN.

OneDrive uploads would only work for me over Mullvad without crashing.

I also had Reddit block Czech T-Mobile IPs.