Using DUP as the metadata profile sounds insane.

Changing the metadata profile to at least raid1 (raid1, raid1c3, raid1c4) is a good idea, especially for anyone, against recommendations, using raid5 or raid6 for a btrfs array (raid1c3 is more appropriate for raid6). That would make it very difficult for metadata to get corrupted, which is the lion's share of the higher-impact problems with raid5/6 btrfs.

check:

    btrfs fi df <mountpoint>

    btrfs balance start -mconvert=raid1c3,soft <mountpoint>