@flizzywp
Copying images directly into the editor should not be possible as far as I know. Not sure if this is a TinyMCE-bug or not, but its nothing that I can fix/change by myself because its a WordPress-component which is also used in the backend for editing pages/posts.
The same holds for the copy&paste. Its default behavior of the WordPress editor so admins can copy&paste parts between posts without losing stylings. As before I cant just “change” this inside Asgaros Forum because the editor is not a part of the forum-plugin. It just uses this WordPress component. If I make changes to it, it will affect the WordPress core and all other plugins which are using the editor in some kind of way.
I would suggest you to check out editor-plugins for this like TinyMCE Advanced which allows you to control the editor.
Here is also an article regarding the styling-problems:
https://sundari-webdesign.com/wordpress-removing-classes-styles-and-tag-attributes-from-pasted-content/
It looks complex and I have no clue if it works. But I definitely cannot add this kind of stuff to the forum-plugin because the risk that I break existing functionality of WordPress or plugins which are used by other users is too high.
If there will be some easy kind of way to implement or adjust this in the future, I can give it a try and will implement it as long as it works reliable.