Since commit 1b999ee00a9ca4dfa732fe69e8f3b44ed5319326 (*1), footnote labes are enclosed opening h5 tag and closing h3 tag.
(*1) http://git.savannah.gnu.org/cgit/texinfo.git/commit/?id=1b999ee00a9ca4dfa732fe69e8f3b44ed5319326 -- Kazuhiro Ito
Since commit 1b999ee00a9ca4dfa732fe69e8f3b44ed5319326 (*1), footnote labes are enclosed opening h5 tag and closing h3 tag.
(*1) http://git.savannah.gnu.org/cgit/texinfo.git/commit/?id=1b999ee00a9ca4dfa732fe69e8f3b44ed5319326 -- Kazuhiro Ito