iPhone 13 mini with iOS 15.1 randomly dropping calls after a couple of minutes...

I'm using 15.1 since I bought my iPhone 13mini, so I can't say if calls would be dropping with an earlier version, but now, no matter what I do, calls keep dropping randomly. I've restored to factory settings with no backup restore to prevent any clutter. Disabled 5G to prevent issues with sparse 5G signal. Switched to eSIM to prevent issues with a loose Sim card. It happens with even with 4 bars of LTE signal, while laying on my desk during a call through AirPods. I was told in a certified reseller store many ppl are having the same issue now and that it's probably a problem of the iOS 15.1, but my daughter and wife are also using iOS 15.1 on iPhone 11 and iPhone 12 and all is fine there, so it would have to be specific to iPhone 13 line or just 13 mini only. I've contacted Apple support to verify it's a known issue, provided all the info and a phone diagnostics. There was even planned call from another support (some higher-up?), but anytime they called me back, it was just a computer telling me I need to wait for an available operator, so I was waiting once 5 min before my phone dropped the call. Next try I was waiting 29 minutes before my phone dropped the call again. Still no operator. I was furious! They are calling me about call drops issue and let me wait on the line forever so it's dropped eventually. I can't swap phones easily with the eSim. All my older phones can't use it.

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