Som svar til Piiieps & Brummm.

That's because most (all?) Mastodon-servers strips away everything in MathML except the annotation-part, which contains the original LaTeX, and add $$ using the recomendation in #fepdc88 https://fep.swf.pub/fep/dc88/fep-dc88.html

The original ActivityPub-content looks like https://browser.pub/https://aslakr.folk.ntnu.no/2025/12/en-mathml-blokk/