I have learned not to jump the gun here - pal is new and they are working out bugs. I am earning money by using their tag and getting airdrops of other coins because I am in pal. I do not visit the site now since I am too busy otherwise to mess with it.

Does anyone know what actually does happen to rewards if I upvote post on Steemit published by someone, who doesn't have account on PALnet?

It just means you did not use your voting power in pal. You have less of a disparity than most of us so you must be voting while you are in there:
https://economicstudio.github.io/vp/?a=crypto.piotr&t=PAL