Płacheta graduated from RB Leipzig's youth academy and began his senior career in Germany with Sonnenhof Großaspach before returning to Poland where he played for Pogoń Siedlce, Podbeskidzie and Śląsk Wrocław.
In international football, Płacheta represented Poland at under-age levels before making his debut for the senior national side in 2020.
[10] Prior to the 2018–19 I liga, Płacheta signed for Podbeskidzie Bielsko-Biała,[11] and made 25 appearances for the club that season.
[16] Płacheta joined EFL Championship club Birmingham City in July 2022 on loan for the season.
[17] He scored his first goal on his second appearance, at home to Huddersfield Town on 5 August, when he drove the rebound from Jordan James's blocked shot past the goalkeeper to give his side a 2–0 half-time lead; the match ended 2–1.
[21] He made appearances in ten consecutive games since joining Swansea, before picking up a hamstring injury in late March that kept him out of play for the rest of the season.
[23] On 15 July 2024, Płacheta signed for newly promoted Championship club Oxford United on a free transfer.