Context: The COVID-19 pandemic permanently altered workplace structures, normalizing remote work. While flexibility has well-known benefits, critical evidence highlights challenges with fully remote arrangements, particularly for software teams.

Objective: This study investigates how employee resignation patterns evolved across different work modalities - onsite, remote, and hybrid - at Ericsson, a global developer of software-intensive systems.

Method: Using HR and exit survey data from 2016 to 2025 for technical roles in Ericsson Sweden, we analyze how tenure, onboarding modality, and reasons for resignation relate to attrition trends before, during, and after the pandemic.

Results: Our findings show a marked increase in resignations from mid-2021 to mid-2023, especially among employees with less than three years of tenure. Those onboarded during the fully remote period were significantly more likely to resign early, and this pattern persisted even after Ericsson enhanced remote onboarding practices. Conversely, retention improved after the introduction of structured hybrid work policies, and survivability curves returned to pre-pandemic levels.

Conclusions: Our findings suggest that fully remote onboarding, despite structural support, may hinder the formation of organizational attachment and belonging, increasing early attrition. In contexts like software engineering, where onboarding heavily relies on in-person mentoring, frequent peer interactions, and on-the-job training, selective return-to-office practices for new hires and their teams may help restore cohesion and long-term retention. These insights can guide HR leaders and policymakers in crafting post-pandemic work practices.