I can't imagine how a pin-on bucket (48", 50", 54", 60" in the Kubota B series case) or a factory QA could possibly cause warranty issues, any more than a different bucket on a Mahindra would. The loaders will only lift so much before going into relief, and a QA isn't going to affect that. The easiest way to damage a loader is with a factory-approved set of pin-on forks (providing maximum lift capacity near the pivot pins) carrying a long heavy item (long moment arm) over rough terrain. That can put enormous loads on the loader frame and hydraulic rams - enough to cause damage.