In his first career game in week 3 of the 2021 season, Bruener made eight tackles and forced a fumble in a win over Arkansas State.[2] In week 9, he earned his first career start versus Stanford, where he finished with 16 tackles with one and a half being for a loss, a sack and a half, and a forced fumble en route to being named the Pac-12 Conference freshman of the week and the Pac-12 defensive player of the week.[3] In his first collegiate season in 2021, Bruener totaled 70 tackles with two and a half being for a loss, a sack and a half, two forced fumbles, and an interception.[4] In the 2022 season, he tallied 45 tackles with three and a half being for a loss, and a pass deflections.[5] In week 12 of the 2023 season, Bruener recorded 14 tackles, a forced fumble, and a pass deflection in a win over Oregon State.[6] During the 2023 season, he notched 86 tackles with two and a half being for a loss, three pass deflections, an interception, and a forced fumble,[7] earning honorable mention all-Pac-12 accolades.[8]