Depending on how you use those videos, it might be sufficient to use a different media player. Have you tried VLC or IINA?
Depending on how you use those videos, it may be needed to make a new, better conversion, that includes audio in the proper format (I would go with AAC audio). Have you tried making video conversions with HandBrake?
Else try getting more analytic information on these source video files from a tool called Invisor Lite (or any other tool based on MediaInfo). Maybe you can share that result for better assessment. It is expected that the codec information is similar for files from the same origin.
