Hey I’m really not sure that I can, since I don’t know Brave for iOS, but I’ll give it a try.
Firstly, just to make sure we are talking about the same Autoplay function, can you check that Autoplay is set to Blocked under Settings → Security & Privacy → Sites & Shields Settings → Permissions → Additional Permissions (i.e. brave://settings/content/autoplay)?
Assuming that is the case, could you disable any extensions that you may have installed, just in case they are overriding your browser settings? Alternatively, you could test this with a fresh Brave profile (again setting Autoplay to Blocked there), or with a Private window (if you don’t allow extensions in Private).
At first, the issue seemed to me, at least, to be something that your Brave Browser settings might resolve.
Because I am not a regular video observer, I thought that @Go-go_duck (who seems to know about video), might be able to help you.
But now, unless you can fix the issue by using the Brave Browser for iOS “Clear Data Now” function . . . followed by quitting everything on your iPad and performing a full Restart as recommended by Apple: