Seperator block has updated and become quite ugly

Hi Team

We have a webite and a subdomain, and recently our subdomain automatically updated to the latest version of Wordpress, but the main domain did not. Not sure if this has been the cause, but since then, the seperator blocks on our subdomain have become quite bold and to be perfectly honest, ugly!

Is there a way we can revert this block back to show as it was showing. Here are links as examples:

Photo of the new format of the seperator block, which we don't like: https://www.solofemaletravelers.club/wp-content/uploads/2021/09/New-line-format-we-dont-like.jpg

This is currently how the seperator is displayed across the subdomain https://tours.solofemaletravelers.club/

Photo of how it was before Wordpress updated, and how it still displays on our main domain: https://www.solofemaletravelers.club/wp-content/uploads/2021/09/Old-format-line-we-like.jpg

Ideally we would love to get this thin grey line look back because we really hate the new update and how bold and doubled it is.

Any help would be MAJORLLY appreciated. Thanks!