How to remove the "original frame rate" tag?

[Selur]

So when I apply the setting 'scale output frame rate' under speed settings to 29.97 it's not actually changing the video frame rate, it's just a container flag?

No, that only works when reencoding, and then the frame rate of the stream should change.
If it does not that's a bug.

Since you didn't really share any details on what you are doing I'm just guessing what is happening.
-> share proper details if you want a better assessment.

Cu Selur