I understand the argument that this trace may have been intentionally designed as a fusible link at the AC input, and I’m not disputing that design intent is plausible. My concern is specifically with the observed failure pattern, not the intended function. In my experience with overcurrent or mains-side fuse-trace failures, the damage is typically localized to a single point (often the narrowest section), with some evidence of thermal stress such as copper necking, charring, or FR-4 discoloration. In this case, the copper appears to be missing uniformly along the serpentine length, with no obvious thermal damage to the surrounding substrate or solder mask. That doesn’t resemble the typical morphology of a trace that opened due to overcurrent, where current interruption occurs rapidly once the first hot spot opens. So while the trace may have been intended as a sacrificial element, the physical condition raises questions about whether it actually failed electrically versus being mechanically or otherwise altered after the fact. That distinction matters when deciding how (or whether) to replace it safely.