In 2018, Lienert showed strong SANFL form before having an arthroscope on his right knee to repair his meniscus,[5] sidelining him for two months. In the lead-up to the match against Greater Western Sydney, coach Ken Hinkley confirmed Lienert would debut, commenting "he probably would've played well before this (if not for the knee surgery) ... he's playing some really strong football".[6]
Lienert was delisted by Port Adelaide at the conclusion of the 2021 AFL season, but was subsequently picked up by St Kilda as part of the supplemental selection period (SSP). Lienert made his St Kilda debut in Round 2, 2022 in the Saints' win against Fremantle. Lienert managed 11 games before getting delisted at the end of the 2022 season.