Background: Agile methodologies emphasise iterative development, customer collaboration, and flexibility in software development. However, challenges arise when agile practices are adoptedin larger projects. Process inefficiencies and redundancies, knownas process debt, result from the compounded complexities of expanding agile processes and workflows. However, strategies tounderstand and tackle it remain markedly inadequate.Aims: This study investigates process debt types, causes, andeffects in large-scale agile development and its connection withtechnical debt.Method: In this case study, we conducted fifteen semi-structuredinterviews with a Nordic IT company, primarily focusing on telecomrelated products like 5G secure solutions, testing tools, and basestation software. We performed a thematic analysis to examine thedata qualitatively.Results: The thematic analysis identified five process debt typeswith 28 sub-types: documentation (3), roles & responsibilities (5),synchronization (5), inefficiency & unsuitability (12), and infrastructure debt (3) identified causes and effects of process debt andidentified the correlation of process debt to technical debt based ondescriptions from interview data and researchers’ insights.Conclusions: Process debt, stemming from flawed agile practices in large-scale development, causes inefficiencies, reduces quality, and extends timelines, risking technical debt. Its managementis essential for the success of these projects