Atlassian doesn't even have consistency within single products! I'm using Jira Cloud at work, and while most fields support markdown (e.g. three backticks to start a code block) there are a few that only support Jira's own notation (e.g. {code} to start a code block). It's always infuriating when I type some markdown in one of the fields that doesn't support it for some inexplicable reason.

In Confluence... the same emojis look different on page title on the sidebar vs the body. Two different font families.

It's incredible.

The thing I dislike about Atlassian is everything from Atlassian

Thankfully these days I spend most of my time in Confluence, which supports Markdown