This is a known problem with FModel (and the underlying library is uses, CUE4Parse). They are writing incorrect data in their PSKs. I reported this bug a couple years ago and they still haven't fixed it. If you want this fixed, you'll need to make some noise on the bug report, because no one is currently working on it.
https://github.com/FabianFG/CUE4Parse/issues/106
In the future, use the link under "Report Issues" to report a bug to the GitHub.
I don't know where to submit a bug. But I will use review as a Bug Submit instead. I wanted to let you know that there's issues with models' shape keys. I have tried to extract models through using Fmodel then I had to import them in Blender 5.0 with your script. It was fine working. But These models get broken shape keys. I have tried everything to fix these issues. But I couldn't get models fixed. Their Faces aren't fully fixed. I'm not sure if it's Unreal Script's or Fmodel's faulty that's causing models to have broken Shape Keys (Morphs). It happened to Texas Chainsaw Game's models when I used Fmodel's new version before and I had to use old version to extracting them with fixed shape keys. But New Games aren't included in old version. I used Fmodel's latest versions to getting Models from new games are supported in only Fmodel's latest versions. I was wondering. Can you fix the script, please? thanks.