This article presents the behaviour of online sellers (including marketplaces) – so-called e-shops – that violate consumer protection regulations. This primarily concerns prohibitions on unfair commercial practices, but also prohibited provisions of the statute of these entrepreneurs. The study focuses on the decisions of the President of the Office of Competition and Consumer Protection (UOKiK) enforcing these regulations. This has occurred particularly over the past few years, reflecting the dynamic development of e-commerce and the increasingly frequent use of new forms of influencing online buyers (consumers). The article analyses the relevant legal regulations in this area to determine whether they are adequate to ensure effective consumer protection against unfair practices, particularly the use of deceptive interfaces (dark patterns).