Please help with vid downloading with drm

[yy0901]

I got the KID and hex key which is fine,
but I cannot download with the

----------------------------------------------------
Decrypted successfully
Merging .....
mkvmerge v57.0.0 ('Till The End') 64-bit
Error: The type of file 'decrypted.mp4' could not be recognized.
------------------------------------------------------

I'm thinking that it would be the vid problem which got exxtracted and not decrypted properly for some reason.
Also the website changed its interface and the license that they were using so got a bit trickier
I cannot see 'cookie' in their license when I open up the dev tool so I'm confused,
I should probably change the python script that I am using but at the same time, I got no clue what to put as the 'header'

"mpd_url": "https://g-aegis-naver.pstatic.net/weverse/owfs_rmc/read/weverse_2022_06_25_0/cenc/d209870a-f430-11ec-a2bf-a0369ffc8178/stream.mpd"
"kid": "89e885ccce493727e80b404eebe41eff",
"hex_key": "7c77c3e889a5646feadc48ab43833ab5"

Please help if you can extract and merge

[[ss]vegeta]

yt-dlp downloads just fine

ytdlp.exe --allow-u -N 8 -f bv "https://g-aegis-naver.pstatic.net/weverse/owfs_rmc/read/weverse_2022_06_25_0/cenc/d209870a-f430-11ec-a2bf-a0369ffc8178/stream.mpd" -o help.mp4

WARNING: You have asked for UNPLAYABLE formats to be listed/downloaded. This is a developer option intended for debugging.
         If you experience any issues while using this option, DO NOT open a bug report
[generic] stream: Downloading webpage
WARNING: [generic] Falling back on generic information extractor.
[generic] stream: Extracting information
[info] stream: Downloading 1 format(s): 1
[dashsegments] Total fragments: 59
[download] Destination: help.mp4
WARNING: The download speed shown is only of one thread. This is a known issue and patches are welcome
[download] 100% of 118.61MiB in 00:05

mp4decrypt decrypts just fine with

mp4decrypt.exe --key 89e885ccce493727e80b404eebe41eff:7c77c3e889a5646feadc48ab43833ab5 help.mp4 help_dec.mp4

[Attachment 66154 - Click to enlarge]