In this study, we explore the effects of self-reported or suspected generative artificial intelligence (GenAI) use in essay writing on peer assessment and revision patterns among a group of early student adopters. The data were collected from a higher education course, where students engaged in a group peer assessment activity, and analysed using a combination of descriptive and inferential statistics, along with Epistemic Network Analysis. The results indicate that early adopters of GenAI tools had lower grades and self-assessments, suggesting they relied on the tools due to writing challenges. GenAI use did not improve final grades, but students made more revisions. Peer feedback was less specific and more positive for GenAI-assisted essays, with lower-quality feedback when GenAI use was suspected. These findings highlight how GenAI use can alter PA dynamics and underscore the need for further research to better understand these changes and develop targeted strategies to support students.