When posting links to SE posts in comments, where links are not converted to links with titles, the tooltips for those links are not capitalized.
For example, this is a bare link with an uncapitalized tooltip:
And this is the actual post with the title capitalized:
Note that the bare links I'm referring to above are the ones which are copy-pasted from the address bar or by right-clicking the title. Bare links which are copy-pasted from a question or answer's Share box do not have tooltips as they don't have slugs.