BUG: CSS added via custom code persists after custom code component is removed

This is not related to the core and should be addressed at the plugin level. Please create the issue there and we'll try to figure out the right approach.

@stpp2 This is not really a bug; it's more of a feature. :)

Try using clearStyles:

https://github.com/GrapesJS/grapesjs/blob/d48e1e34a9fa363dcb83fdcca53a89563db17063/packages/core/src/editor/config/config.ts#L260-L272

Yeah clearStyles is already enabled in my case, but that doesn't seem to work well in many cases. Either way I'd expect the Custom Code component to be somewhat "containerized" so it's not leaving anything in the doc when removed.