They even reported that in Ria.ru (in Russian). I would be offended too. It is one thing when USAF paints its F-15 or F-16 of "aggressor squadrons" in RuAF colors, but painting F-35 and calling it a Russian Air Force combat aircraft? This is insulting.
What kind of Russian aircraft should this F-35 imitate? SU-30SM, SU-35C? More like Il-2 or Yak-9, maybe MiG-15? Russians are livid, at least F-15 or F-16 are good aircraft. But the worst is, of course, sticking SU-57 livery on F-35 flying brick. That is an absolute no-no.
On the other hand, it is, probably, the only chance for F-35 to realize its dream to be a world-class combat aircraft and turn and burn with the best of them--to pretend to be the one. In related news, all modern Russian combat aircraft ranging from SU-30 to SU-57 are netcentric capable machines, incorporating latest in data-sensor fusion and advanced sensor suite. Russians do it differently. Russian Air Force light attack--fighter--trainer Yak-130 has, literally, presets for emulating very closely type of flying by F-16, F-18 etc.
I don't know if it has presets for F-35. I am not sure it will be happy with those, wink-wink.