The moment happened at some point during the Chiefs' "Monday Night Football" tilt with the Saints ... when Taylor, Britt and Blake Bell's significant other, Lyndsay Bell, posed for a pic together in an Arrowhead Stadium luxury box.

Taylor and Lyndsay -- with some beverages in tow (get a load of Tay Tay's Travis Kelce-themed cup!) -- placed their hands on Mrs. Mahomes' stomach for the snap ... and then they all smiled as the camera's shutter went off.

Of course, there had been speculation Taylor and Brit were on the outs ... as the two appear to be on very different sides of the political aisle. But between this photo and the big embrace they shared just prior -- it seems those rumors can be put to bed.

As for the pregnancy -- it's not only Brittany's third ... it's also the third time the ladies have celebrated an impending birth at a Kansas City game.

The trio posed for pics together while Lyndsay was pregnant twice last season -- something Brittany actually acknowledged in a caption on the photo.

"Same girls," she said, "new bump."