Normally we try very hard not to break any plugin, by ensuring that the API remains backward compatible and by deprecating rather than removing methods.
The one exception was the move from CodeMirror 5 to CodeMirror 6 for the Markdown editor. Even in that case a compatibility layer was developed and many plugins still worked fine, but some may have slip through the cracks and remain incompatible, including maybe this Emoji one.
In that case it's still possible to revert to the old Markdown editor if you prefer, although it means that newer plugins won't be compatible.
Another exception is the macOS theme plugin which is modifying the CSS and for this we don't currently provide a stable API, so it often breaks between versions.