Google for VictronConnect beta and download latest beta available, it fixes the crash on connection. There is still a problem with Monterey: pairing to a new product fails ending up on a PIN code request loop. The paring issue seems to be a bug in Monterey since it does not continue with the pairing after the pincode has been entered.

There is a patch available for Qt that fixes these crashes, I can confirm that it works. Search for it in the bug tracker, perhaps it is already included in one of the releases.

Does your custom BLE device implement PIN code pairing? If so, does pairing work for you?