Add ESIM/data/cellular plan is missing

Hello!

I’m experiencing some troubles with my eSIM cellular plan. Previously I was using multiple sim cards: one physical nano SIM, as well as 2 more ESIM plans from different carriers. It worked properly until at one point the display showed "SIM Failure" and disabled the ESIM active at that time. The nano-SIM is still working, but ESIM plans are unavailable.

When you move to the cellular settings, clicking on one of the ESIMs brings up the message "Last Line No Longer Available". It deletes the ESIM plan upon clicking “OK”. Every time I restart the phone the display shows “SIM Failure”

It is not possible to add a new ESIM:

1. There is no "Add ESIM/Cellular Plan/Data Plan" field in the cellular settings. It’s just gone, but it was always there before.

2. When you scan the QR-code the "Cellular plan" button appears, but it's unclickable and nothing happens if you press that button.

Important to know:

1. My device: iPhone 11 (A2221). Device is completely carrier unlocked (and always was), not for the Asian market, only GSM network applied (no combination of GSM & CDMA). The device supports only one nano-SIM (double checked the SIM tray).

2. According to 2 carriers (which I used before the problem occurred), there are no eSIM restrictions on their side. Moreover, they cannot assign a cellular plan to me, since they don’t offer that feature (EMEA region if it helps).

3. Screen Time does not block any changes in cellular plans.

4. I don’t have an MDM profile.

What's already been done:

1. Network settings reset.

2. Hard reset.

3. Software update.

How can I resolve this issue? Is this some kind of hardware issue? I've read many forums on this topic, but there seems to be no solution. Any ideas will be much appreciated. The one-year warranty has already expired.