We don't have any instances with more than 500 users so perhaps that's the key difference here. We also don't have any PMs or 'admins' that do heavy handed top-down "you must use it this way" configuration.

We do have all product owners meet up at least once each month and the project collaboration methods are often on the agenda to make sure we don't end up with too many different workflows that are essentially duplicates of each other. Besides the workflows (mostly oriented around kanban boards and backlogs) we just make sure that collaboration across teams use compatible workflows and epics so you don't have to copy-paste information and instead just share stuff.

Each individual team is no larger than 8 people, most are smaller.

We did have people actually migrate away from JIRA because they didn't need the features, not really because they were required to move to the Cloud instance. But the fact that they now had to move at all made it easier to switch (some went to Redmine for some reason, others went to Git-SaaS integrated boards).

Strange... While I have seen many poorly configured PM tools (including more badly configured JIRAs than useful configured JIRAs), I haven't really had any performance issues or UX issues with the ones I work with directly. It's not 'slower' than say, GitHub and GitLab's boards, or Trello.