We noticed that generating of header anchors was changed and our anchor links were broken.
In v.2.2.9 was:
<h3><a name="H3H4-UTF8notASCIIstring"></a>UTF8 not ASCII string</h3>
The code works properly everywhere.

But in v. 2.4.4 is:
<h3 id="H3H4-UTF8notASCIIstring">UTF8 not ASCII string</h3>
The code works properly in IE and Opera.
Firefox can not work with anchors by an id, if the id contains not ASCII string (e.g. Russian).

I can suppose it is not a Confluence bug, it is a Firefox problem.
But it would be great if you could manage to find a workaround of the problem, e.g. rollback of generating of header anchors to v.2.2.9