[ransackdev]

A plugin is a separate code module that wordpress loads, surely those are not bound to the wordpress core license. Extending wordpress with non-wordpress owned code does not grant them the right to push their license onto somebody else's completely unrelated code. If that were true, nobody would ever be able to sell a proprietary app on any linux distro. GitLab is open core yet extends the functionality with enterprise under a different, proprietary license.

[mthoms]

There's no legal precedent yet, but WordPress plugins/themes are widely considered as being GPL because they're a "derivative" work.

Or, at least the PHP code in those plugins/themes are - possibly not the CSS + assets.

https://kinsta.com/learn/wordpress-gpl/