Nia Hill accompanied her comedian husband to the UFC 295 event Saturday night at NYC's Madison Square Garden -- and during one of DT's on-camera moments on the jumbotron ... she flipped the bird, which many have taken to be directly targeted for Trump.

Frankly, it's hard to tell if this F-U was, in fact, intended for The Donald or not. It looks like Trump is in the same aisle as them, but slightly angled ahead of them as they're seated.

Nia throws up two single-finger salutes right at the UFC team pans to them ... but it seems like she's perhaps doing it straight to the camera itself, as opposed to DT who's to her right. Whatever her intention was, right-wing Twitter certainly took it as an insult to the ex-Prez.

As a result, he's getting a ton of hate from conservatives ... 'cause they see his wife's would-be gesture toward Trump as a reflection of his own politics -- even though he holds that pretty close to the vest.

Burr occupies this nebulous comedy space ... at times, he comes out swinging against "wokeness" but also rails on right-wingers just as much. Dude's an enigma, for sure -- and more importantly, there aren't many interviews he's done where he straight-up craps on DT.

Now, he's in the crosshairs of MAGA loyalists ... who are still very much with 45. The UFC crowd also appeared to welcome his presence ... as he rolled in with Dana White, Tucker Carlson and Kid Rock.