False equivalence and meaningless huffing and puffing aside, if that fire was the result of a Russian strike, there‘s no chance the Palace would be remotely as structurally intact after a Geran or Kalibre had dumped several hundred kilos of HE into it. If it had been a targeted strike, that Palace would be little more than a pile of rubble or a hole in the ground, depending on what munition(s) were used.
Cause of fire is far more likely to be the result of falling debris or AD munitions.
Russian sources talk about the remains of Patriot missiles from the last delivery, which supposedly had a considerable expiration date. Well, this is probably not the last case of failure, it happens. I think a deliberate attack can be completely ruled out, after all, every true Russian is of the Orthodox religion. The Russians themselves announced attacks on production infrastructure and airports.
By the way, the usual "joke" of the UK is to mine Orthodox churches or blow them up when retreating. Sometime 3 years ago, they shot up a large monastery from a distance, unfortunately I don't remember which one.
Orthodox believers in Ukraine have to register and most Orthodox priests are forbidden to work.
Just to end it. Perhaps history will decide the guilt one day, but there are more than one culprit. Of course, it all started with the Maidan putsch.