I confirm this. Latest firmwear does not help and iOs and Android have same problem.
Hi, I signed up here just to add some information for this issue.
When I have it on a bare 18650 with no BMS board, I have no Bluetooth issues.
However, using a pouch type battery with a BMS board attached seems to cause the constant BT disconnection issue - I will try bypassing the BMS board temporarily and report back.
The custom firmware allocate a random pin even for device without screen. You can see the PIN on serial logs. Hope it helps.