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Permission issue with dumped android (and encrypted) /data partition

Recently I had a issue with my phone and I wiped it, but before I dumped (

adb pull /dev/block/sda29

) all the /data partition that was on my phone.
After that I mounted the image simply with

sudo mount ./sda29 /mnt/data/

the file mounted normally but now I’m not able to browse inside /mnt/data/media/0 folder: it give me an error when trying to list files (even with root shell):

ls: cannot open directory '.': Permission denied

I think is caused by android internal storage encryption, but then how can I decrypt/access those files?
(My phone is a Xiaomi Mi 9 SE, with android 9 installed)

Thank you very much.