Jellyfin video stutters on some files (all MKV it seems)

Hello fellow selfhosters! I reformatted my USB hard drive from exFAT to XFS because I needed a filesystem that could handle hardlinks. I remounted the hard drive and now jellyfin webUI has a severe stuttering problem on some videos, all of them are MKV but it may be a coincidence. On android (using exoplayer) the same files...