Colour issue during 1080p export

[tracyb39900154]

I'm trying to export a clip, all filmed and edited on iPhone 13 pro max. 
however, in the last part of the clip, the colours come out super faded when I export in 1080p. It's weird because a part right before, which was originally from the same video but just cut, comes out perfectly. 
I don't have this issue when I export in 720p.