How to attach QuickTime's automatically generated subtitles to a video?

I have a question about Quicktime in MacOS 27. My question seems to be the reverse of what many are reporting. QuickTime seems to be working fine and it opens all my old MP4 files. But what I am finding is that with the Subtitles toggle set to On, QuickTime appears to be creating the subtitles on the fly. I see subtitles appear in movies that I know very well don't have them (e.g., my iMovie-created vacation videos). This is a cool addition if it's not just a fluke. Assuming it's part of the new MacOS AI, is there any way to attach these subtitles to the video so I can watch them, say on my older iPad (which doesn't support the new Mac AI)?