They’re apparently trying to switch from using something like confluence markup to using the markdown that just about everyone expects now... https://support.atlassian.com/jira-core-cloud/docs/markdown-...

But like everything Jira, they can never seem to find the energy to redo everything all at once, so they do it one screen or one section at a time instead... reminds me of how Office apps never improve all at the same time, just a bit at a time... in one app... if you’re running the Cloud version...