For starters, I recommend against using backup plugins. At least on our hosting, they tend to break more often than not, and generate high server load which may result in your account getting suspended. If you want to backup your site, we recommend to just backup the files and databases by hand instead: How to backup your website
I also did some debugging on your site to figure out this issue. It did take me some time to spot the issue, but at a few places, it said “There has been a critical error”. This usually means a PHP code crash. Enabling WP_DEBUG showed the issue was in the WordPress core, not a theme or plugin. And I saw some notice saying a WordPress update failed.
So I think either you or the WordPress auto updater tried to update your site to WordPress 6.1, which resulted in your site getting corrupted: How to safely update to WordPress 6.1 (and fix your site if you didn't)
Fortunately, you can probably fix it without losing any data by following this guide: