4G/LTE does work only on slot 1 when two sim cards are inserted

With current focal RC 2023-W12/4 and also reported on devel the usage of LTE/4G is limited.

• one sim card inserted: works on either slot
• two sim cards inserted: works ONLY on slot 1, does not work on slot 2

No change to apn settings when swapping cards, so that was not the issue for not getting LTE on slot 2.

Affected devices OP5T (mine) and reported in Telegram dev group has been mentioned for Xiaomi devices, definitely redmi note 7, and possibly others.

Closing the OP5T specific issue in favour of this one here.