The website has a page where anyone can submit a post without logging in and then the post is reviewed by admin and published or rejected. To implement this functionality I used this plugin: [link to cracked plugin removed by moderator]
As I upgraded to WordPress 5.7 the problem is that WordPress removes all the formatting from the submitted content and all content is shown in a single line.
for example, if anyone submits this( https://ibb.co/KqLbvtV ) content from the front end of the site, then this is converted in the block editor to this ( https://ibb.co/9qgW09s ).
When I click the classic block it changes as- https://ibb.co/8D3GLZJ
After the upgrade, all old posts are also converted to a classic block in the block editor but their formatting is still preserved ( https://ibb.co/89mf7Vq).
This issue is happening with the new post submission from the front end.
The page I need help with: [log in to see the link]