[bleakassassin]

Now in the last two versions the HDR on/off has been removed from the power menu - so now it is not even doable to go back to SDR manually

F11 key 

Just out of curiosity, is there a reason you're so reluctant to have HDR automatically disable when stopping play of HDR videos? Many people in this thread have expressed that they'd like for it to work that way, and I wouldn't be surprised if most people who use this fork of Kodi - or any HDR-capable media player, for that matter - feel that way.