Welcome to the forum!
I know that some of my suggestions are poor replacements only, but I'll bring them up anyway.
Doesn't work with plain text, indeed, but does work with indented bullet lists.
The latter can be achieved by exporting the note containing the clip, the former (probably) by a simple copy and paste procedure. Not in the process of clipping, of course, but after the note has been created.
Maybe this plugin can help, but it probably doesn't come close to what you (and me) used to find in Evernote (although I personally never used nested tags). In contrast I find it very useful, that nesting notebooks in Joplin is not as restricted as it is in Evernote or OneNote.