Android devices take upto 10 minutes to acquire cellular reception after boot while roaming

When I boot android device having a SIM on roaming it took around 2-10 minutes to get cellular reception. I've tested this on multiple devices, similar behavior. One interesting thing is, if device is already booted and then I inserted the SIM, it instantly gets cellular reception. For a non-roaming SIM it works instantly even after boot. Edit: The SIM provider told us it's an eSIM, though it looks like a regular SIM card. If you've any explanation on this, could you please share?