Antonio Brown Signed Fan's COVID-19 Vaccine Card Before Final Bucs Game

Antonio Brown was quite the crowd-pleaser before his last game in a Buccaneers uniform ... smiling from ear to ear, taking selfies and even signing a fan's COVID-19 vaccine card!!

TMZ Sports is told ... AB was in the best of moods while chatting it up with fans in the front row at MetLife Stadium hours before his infamous shirtless exit from Sunday's game.

As one fan put it, "He was the most down-to-earth guy and couldn't have been nicer."

But while some spectators sought regular autographs, one fan went one step further and asked AB to sign his freakin' vax card -- and he obliged!!

Of course, the whole thing was a reference to AB's vax status scandal ... when his former chef accused him of getting a fake vax card. While AB swore up and down he was, in fact, vaccinated ... the NFL felt otherwise and handed him a 3-game suspension.

AB was clearly able to laugh it all off as the fan asked him to sign the card ... grinning and embracing the irony as he etched his John Hancock along the bottom.

On top of that, AB posed for pics with fans before the game ... and we're told he was generous to the entire section.

Unfortunately, things changed later on in the day ... as AB made his infamous exit by ripping his pads and jersey off and strolling into the locker room in the middle of the game.

The Bucs and AB have different stories behind what went down ... but he was ultimately released Thursday morning.