Hi all, my idea has worked 
The problem was in my hardware. The day before my business trip Iāve accidentially destroyed one of TZ66D dimmers by short-circuiting output L+N (I didnāt know that switching off the dimmer didnāt mean complete cutting off the power. I hope replacing the fuse will be the only action needed to bring it to life back. But still, itās another topic). Of course in the lack of time Iāve just replaced this dimmer with simple standard switch in order not to leave my family without light in the kitchen , and left for my business trip. And of course I didnāt exclude the faulty dimmer from the network.
Upon my return Iāve updated OH to 2.5 and started seeing the issue discussed in this topic. Looks like it was the first restart after destroying the dimmer, and of course I forgot that I havenāt excluded it from the network. And it seems that it was causing problems listed above, because they have dissapared after exluding the dimmer and restarting the binding.
Sorry for stealing your time, and Happy New Year everyone!