Fermata and marcato always sit outside every other mark on the note, overriding normal side/stack rules

Fermata and marcato must remain unambiguous regardless of what else is attached to the note, so they are placed outside the staff and outside any other stacked mark on that note — the one exception to the otherwise-consistent notehead-side rule (vs-articulation-notehead-side-default): fermata/marcato ignore stem direction and sit above the note (or below, only if the whole passage sits below the staff already).

A fermata on a stem-down note is drawn immediately above the notehead but UNDER a slur or ornament also attached there, instead of outside both.

Gould, Behind Bars, ch. 'Articulation' — fermata treated as always-outside; called out as a named exception to the general notehead-side rule in Read and Ross as well.

This rule needs the notated content and the rendered result together — the score says what should happen, the page says whether it did.