cc @matmarex @Jdlrobson

@cscott is this being served to anonymous users on any of our projects? cc @ovasileva

In T358504#9577013, @Jdlrobson wrote:

@cscott is this being served to anonymous users on any of our projects? cc @ovasileva

Anonymous users of officewiki. (That's only the front page of officewiki!)

Anonymous readers of talk pages on wikitech, eg https://wikitech.wikimedia.org/w/index.php?title=Talk:Main_Page&useparsoid=1 which also shows the "doesn't boldface as you scroll down" issue.

I don't know if T337286: Gadget API for adding buttons to section titles would help here, but mentioning it just in case.

This is a dup of T358452: Vector 2022 dynamic table of contents broken on Parsoid apparently.

Typically when stuff breaks like this it does surface the need for a stable API so yes T337286 would be helpful. We've pretty much locked in our sprint for the next 2 weeks, so I'll make sure we get this prioritized for 2 weeks time. If you need to roll out to other wikis sooner than that, then our teams will need to talk before then regarding team priorities/OKRs.