This thesis discusses how online disinformation and hostility against the press impacted some of the journalistic practices of mainstream news outlets in Brazil under the administration of former far-right president Jair Messias Bolsonaro (2019-2022). The period marked a decline in press freedom in the country, with news outlets and practitioners facing disinformation campaigns, threats, restricted access to government data and events, unjustified lawsuits, and attacks on and off-line. Reports produced by national and international journalism entities in the period have linked the rise of hostility against news practitioners in the country to the anti-press rhetoric and behaviours conveyed by Bolsonaro, whose communication heavily relied on social media platforms. The research sets out to understand Bolsonaro's anti-press rhetoric, amplified by his allies and groups of supporters, and its potential effects on the normative practices of journalists. It explores two sets of data. The first, Analysis Stage 1, employs thematic content analysis to describe the nature of Bolsonaro's anti-press messages on Twitter (X), adding to the scholarship on digital populism, one relevant element of information disorder. The analysis suggests that Bolsonaro's attacks on the press incorporate current global populist trends tailored to the Brazilian context. Analysis Stage 2 discusses the views of mainstream Brazilian journalists on their experiences regarding disinformation and harassment, pointing to evidence that some changes and adaptations have happened in their work practices to tackle misleading content and attacks against the press. The analysis shed light on responses required from news outlets and news practitioners concerning normative practices, such as verification, balance, and objectivity, and the consideration of security measures. Both analyses combined point to a need for transformations in news productions regarding the approach to digital populism; they also reveal that the exposure of individual journalists makes their role central to those transformations.