It will sound like defense for NB's behaviour that you witnessed, and I've got to admit I've only watched him play a handful of times, but it sounds a little out of character. Maybe those that have seen him play a lot can weigh in an update me. But I think he may be feeling the burden of being a professional. I think this is his first full year as a pro. He's done pretty well but been stuck around the 100 ranking. That's a little bit of a tough spot, main draw for challengers (not where you want to be) and qualifying for tour level events (again, not where a pro wants to be). With the long season nearing the end maybe he just snapped, not a good look and hope he learns and resets from it. I still think the kid has a higher ceiling. At this time of the year seeing peers like EQ, AM, LT and even Valentine Vacherot have some better results may be bothersome, hopefully he's not chasing others. The wear and tear on the body and all the international travel, man it's got to have it's non-glamorous moments that makes it just plain tough.
I'm betting he comes back stronger in 2026.