Oh, snap! You just got st. Peters-burned!

[Ostap]

"In his speech, just last night, Putin lied some more. [cut to Putin's speech] "Modern Ukraine from the beginning, and it's totality has been created by Russia." [cut to Colbert]: to prove Putin wrong, after he made that claim, the United States embassy in Kyiv tweeted out these four churches in Kyiv dating all the way back to the 10th century, next to the empty forest that Moscow was in the same period. Oh, snap! You just got St. Peters-Burned!"
link with timecode

Hello, everyone. I think "Snap" humorously refers to the "similarity" of the churches at the attached picture (3:27 at the link). Is that right?
And, what is puzzling me, what does the pun "Peters-Burned" exactly imply?

 

[SoothingDave]

"Oh, snap!" is just an interjection. Like "boom!" It's supposed to signify that one has destroyed one's opposition with a blistering comeback.

Same with "burn!" at then end of a declaration, meaning "I have just completely humiliated you!"

St. Petersburg is a famous city in Russia. He just put the "Burn!" is the place of the last syllable, to make it a Russia-centric comment. For comedic effect.

 

[Skrej]

A 'burn' is a joke, insult, comment, or retort that is particularly effective, insulting, or humiliating. It's also used as a verb, meaning to make such a comment.

I don't know for sure if the slang term derived from the notion of a comedic roast, but the similar term 'roasted' which does stem from the comedy roast, is also used as a slang synonym for 'burn' sometimes.