Update on the ongoing matter:
I revisited the Kolkata service center where their lead technician reevaluated the problem and forwarded the evidence to Nothing’s technical team. After some days, I received a call from the service center confirming that they were granted permission to replace the display panel. The internal team acknowledged the presence of a ripple effect on the screen glass surface. (Likely because now it was re-escalated from upper management).
I made another trip to Kolkata to have the display panel changed. Before replacing it, they showed me the new panel for verification. Despite the new panel not being entirely flat (still having some ripple effects), it was an improvement compared to the one I initially received with the factory-sealed mobile handset.
Therefore, the display has been successfully replaced.
I’m grateful to the community members for keeping the discussion active and bringing it to the attention of upper management.
A special mention to Tom and @Derren , as it seems the issue here isn’t simply light refraction but rather a MAJOR QUALITY ISSUE from your vendor’s end. I have no complaints against the brand Nothing. It is the most optimized 8+Gen1 I am using; excellent battery backup and a well-tuned display. However, the issue needed acknowledgment, and “fortunately”, it gained the necessary attention in my case.
I extend my gratitude to Rob ⚡️ for re-escalating the matter to your internal team and for not selecting a “scientific explanation” as the best answer and marking the issue as answered.