Object-fit on background video doesn't apply until after page is loaded

On mobile, the object-fit property of the Background Video component doesn’t seem to apply until after the video is loaded, causing a weird flash of the video at its original aspect ratio before it fills the container:

I found a similar post re; Wordpress so I think that may be a browser / CSS issue rather than Webflow, but I’d love to know if anyone has found a workaround for this.