UPDATE: I just installed “fresh” and “clean” (no add-ons etc.) version of 19.1 ona different SD card and it produces EXACTLY the same results when trying to play anything HEVC/x265 
…so I guess now it’s time for rebuilding my previous OSMC on Leia…
…unless someone has a solution/fix for this…
EDIT: Also I just realized that I was supposed to turn on debug logging etc. and all I gave is just a “simple log” right? …but now that I checked that it’s behaving the same on a fresh install it should be a problem for everyone on 19.1 and 3b+, and therefore it’s not needed any more
…I might be wrong though, if it is so then correct me.
EDIT #2: Also there’s already a topic regarding HEVC problems here:
…so, I guess admin should merge them/close one (IDK what forum admins do in such a situation). BTW: I changed the topic - removed no support for eminence skin, as I found that “Arctic: Zephyr - Reloaded” is a good (although not as complete) alternative for now.