This is the procedure for how to disable the pop-up “Welcome to Block Editor” in WordPress with custom CSS code.
If you also feel constantly annoyed by the pop-up message “Welcome to Block Editor” in WordPress, then you are not alone. The WordPress developers obviously failed by relying on cookies, which mondern privacy concerned users clear often. Until this problem is resolved, despite 6 months of complaints from users, you can disable it by adding the following CSS code as custom CSS to your theme.
display: none !important;