"Entirely correct. In the autopsy setting, macroscopically antemortem clots tend to be slightly more rubbery and firm to palpate, more homogenous in colour and "take the shape" of the vessel. Post mortem clots are softer, tend to show a split into plasma and RBC (like in a drawn blood sample that's left to sit too long without EDTA or other agents) with a so called "chicken fat" appearance."

https://www.reddit.com/r/pathology/comments/xot2pg/whats_the_difference_between_antemortem_and/