the only damage I can think of is maybe too much wind stress, the plant in right next to a fan. the other plants look good some leaf damage but not much. all these plants had a rough start and had stunted grow. I didn’t have a heat mat so the seedlings were cold and didn’t grow well until I transplanted. the damaged bud is on the lower growth its hard to tell because the plant was mainlined. hope the additional information helps and I added more pictures of the grow and other plants. the blumat system was installed 2 days ago after the damage was discovered.
I called AC Infinity when using my fans and they say they are rated to run max 18 hour intervals and require a 6 hour rest for the best mix of use and life span. I have all of mine on that schedule as a result.