I have now installed the (more than 1 year old!) version 4.22 of Garmin Connect Mobile (from apkmirror) on my Moto G7 Power (Android 10) smartphone. With this version 4.22 of GCM the BT pairing with my Garmin Edge 530 (FW 6.0) succeeds immediately and all BT connected features work as expected. Wtf...?