Exporting video creates weird horizontal lines - HELP

[Lainie5F88]

I try to export my video for tiktok/to save to iphone and in both google drive/dropbox it is unable to save to phone, but it is able to upload to tiktok but only with weird horizontal lines.

This is an example of what they look like - I'd love help to fix this. 

[John V Knowles]

What export settings are you using?