Wild guess: If you have a prepaid eSIM in roaming mode (such as you'd get from silent.link) chances are that it doesn't work with some networks in your current roaming profile. I have this issue sometimes and here's what I need to do:
Try connecting to a different network (in your eSIM settings, disable "Automatically select network" and try connecting to another provider). Be aware that you pay different prices on each network.
If no provider let's you connect, try changing your roaming profile. Open the SIM Toolkit App (via Settings -> Apps -> All Apps) and find the profile settings. I have 3 different profiles available (the active one is marked with a *). After changing the profile, restart the phone, wait 10 minutes and repeat step 1.
Hope this helps you, when I activated my first roaming eSIM it took some time and I was nervous it wouldn't work. In the end it always worked out though.