WordPress has issued a new release just a day after WordPress 5.5.2 caused problems with fresh installs and sites with auto-update enabled were updated with alpha (unstable development) code.
This is not a cause for concern for our clients with Care Plans as updates are managed in a controlled way as part of a maintenance schedule.
To update your WordPress visit Dashboard → Updates and click “Update Now.”
Source: WordPress.https://wordpress.org/news/2020/10/wordpress-5-5-3-maintenance-release/