Some projects like Drupal aggressively discourage premium versions, but I imagine that the WordPress tolerance of the freemium model is partially responsible for its success. However, this also creates a tension that is a big gray area.

Although it has been talked about, the guidelines are not always clear where plugin and theme authors can advertise: in the Customizer (where / how)? On the general plugins page? On the plugin's settings page? On the post edit page? On the update page? And what about on WP.org? Maybe we should have a tab for Premium services?

This might be a good time to standardize some rules. Perhaps in this case, for one-off blocks, have some guidelines and allow a button on the block context menu or block sidebar?

However it is done, it would be nice if the advertising / upsell rules were standardized.