WordPress 5.9.1 contains 33 bug fixes in WordPress Core and 52 bug fixes in the Block Editor.
Since this release contains security fixes, please make you run the update immediately. You can read more by looking at the release notes: https://wordpress.org/support/wordpress-version/version-5-9-1/
You can also see a complete list of changes: https://core.trac.wordpress.org/query?status=closed&resolution=fixed&milestone=5.9.1&order=priority
If you have not done so already – download the update or simply use your existing installation of WordPress to update your site. Either way – this is an excellent time to make a backup copy of your site(s) before upgrading.