overtime in unrated?

my duo and i were playing an unrated as per normal, and we reached a 12-12 situation. all is fine, but then, overtime begins and our team gets to 13. after, the enemy team wins twice, and the game ends in my duo and i's team losing with a 13-15 loss. for context, i play on PC, as does my duo. this was a pc game, and was not on console. the key question: why the hell is there overtime in unrated? that's a huge change, one that i can't find in the recent patch notes, and I played valorant around 2 nights ago and reached a 12-12 in unrated where overtime did not occur. many of my team members asked if they'd accidentally queued comp, as did my duo and i, and now i've been asking around for help. So far, there is one reddit post from a few hours ago asking about a very similar situation. either this is an addition that is not new yet nobody has heard of, a major bug, or a new addition that was neglected to be mentioned in the recent patch notes. this simply does not make sense. any feedback is appreciated.