The 26-year-old joins having spent the last four years in English football, signing for Norwich City in 2020 and most recently spending the end of the 2023/24 season at Swansea City.
Płacheta arrives with plenty of high-profile experience across the Premier League and Championship, while also earning seven caps with his national team and playing in Euro 2020.
Starting his career in Poland, he also had spells in Germany with RB Leipzig and Sonnenhof Großaspach before returning to his homeland to play for Pogon Siedlce, Podbeskidzie and Slask Wroclaw.