Mounting Android 7.0 userdata.img

I am trying to recover user data from a bricked Oukitel K3. The device had Android 7.0 and a MediaTek MT6750T processor. SP Flash Tool enabled me to download the full contents of the EMMC. Then I extracted the userdata.img and decrypted it. (I found the decryption info and keys in metadata.img) I'm now attempting to mount the decrypted image in order to access the files, but I am getting the following error:

$ mount -v -o ro,loop userdata.img /mnt/user_data/
mount: /mnt/user_data: wrong fs type, bad option, bad superblock on /dev/loop0, missing codepage or helper program, or other error.

$ dmesg
 EXT4-fs (loop0): Unrecognized mount option "\\x1cb\\x1d\\xb6T\\xdcW\\xb35\\xe9

The error seems to suggest that the filesystem is compressed in some way - i.e. sparse image. However, it doesn't have the magic header; output of simg_dump.py:

simg_dump.py: userdata.img: Magic should be 0xED26FF3A but is 0x97DCD0F0

Output of file command:

userdata.img: Linux rev 1.0 ext4 filesystem data, UUID=57f8f4bc-abf4-655f-bf67-946fc0f9f25b (needs journal recovery) (extents) (large files)

Output of fsstat command: [https://pastebin.com/raw/sXRS5WSc](https://pastebin.com/raw/sXRS5WSc) Has anyone else ever encountered such issues? It seems that I am very close to getting the data, but I just have no idea how to mount this file.