Algorithmic Biases on X before the 2025 Polish Presidential Election

This study examines whether the default algorithmic feed of X shows politically balanced content to users who follow presidential candidates and Polish political party members before the 2025 Polish presidential election. To address this question, we track news feeds of four sock-puppet accounts and analyze public posts of 485 Polish politicians and related users during the culminating month of Polish presidential election. We find that most of posts shown in the default algorithmic feed of X was from right-wing parties. The user most often appearing in the feed is the leader of the far-right party Konfederacja Korony Polskiej. We study the factors determining the appearance of a post in the feed of X, finding that the visibility of the extremes of the Polish political party spectrum is significantly amplified by the feed algorithm, possibly due to major platform updates following its ownership change in 2022.