Can files from android internal be recovered after using adoptable storage?
your only chance to get files back is decrypt MicroSD Card with correct encryption key. as long as you did not discarded the adoptable-storage by forgetting SD Card or factory reset, they key will remain on device.
therefore you can try to root your device.
be aware unlocking bootloader will erase all data.
you have two possible options:

get a temporary root shell with mtk-su, or

root your device (on locked bootloader) with SP Flash Tool and Magisk Manager


once you managed to access /data/misc/vold you can use linux dmsetup to decrypt your MicroSD Card and access the files
for more information refer to the adoptable-storage tag-wiki
How to decrypt Adopted Storage?