Issues with markdown generating anchors

I am having an issue getting markdown to generate a proper anchor tag when I use headers that are 3 characters and when I have numbers in them. I have the following headers in my markdown

## MDX v5
## SSO

The first one renders as mypage#mdx-v without the 5.
The second one just generates mypage#.

If I add an extra character to the last one it generates the anchor so there seems to be a 4 character minimum which I don’t get since anchor tags in HTML don’t have a minimum requirement. I have no idea why the 5 is being concatenated.