A preprint posted to arXiv in May 2026 examined photooxidative ageing in FFF-printed PLA, ABS, PETG, HIPS and PC after 7744 hours of controlled UV exposure. Researchers used nanoindentation to map hardness and modulus changes plus Raman and FTIR on a subset of samples, revealing surface-limited effects (<10 µm) in most materials. Contrary to the paper’s conclusion of high PLA resistance, real-world patterns show yellowing, cracking and loss of layer adhesion in household prints within 3–6 months, suggesting the isolated UV protocol missed synergistic moisture and temperature cycling that accelerate chain scission. ABS and HIPS embrittled at greater depths, matching earlier findings in a 2019 Polymer Degradation and Stability study on injection-moulded ABS. PC performed best, consistent with its aromatic structure, yet the preprint’s small, unspecified sample set and lack of mechanical testing beyond nanoindentation leave open questions about bulk tensile performance. The work underscores that visible surface degradation often precedes measurable bulk changes, a gap prior combined-weathering studies also under-sampled.