You're welcome. You end up finding the limitations of DJI drone tech with personal experience. With the early firmware: I've had a similar experience with my mini 3 pro.
DJI have addressed the 'excessive battery draw' problem by tweaking...
When you have an external charging source connected while flying, the power lights will show the charging cycle, not SC battery power remaining. I get at least 6 batteries flying out of one full SC charge.
Maybe you need to replace the SC...