I am filing this as a sibling issue to #3995
In the WP dashboard, the "Welcome to WordPress!" block can be dismissed (per user), via a link at the top-right:

We should introduce such a feature as well; perhaps in a way that it can be reused by other blocks too.
GitHub Issue #:
3996
Recent comments
UPDATE: I fixed the errors that I found in the logs. They were related to deleting an old blog content type pulled over from Drupal that was still referenced in one of the layouts. I updated...
missing "add block" in custom layout
Hmmm... this sounds like a bug with Copy Blocks. Would this possibly be related: https://github.com/backdrop-contrib/copy_blocks/issues/26 https://github.com/backdrop-contrib/...
missing "add block" in custom layout
Also this error: Warning: Undefined array key "blog" in summary() (line 63 of /app/core/modules/layout/plugins/access/entity_bundle_layout_access.inc). I did recently delete an old blog...
missing "add block" in custom layout