You mean Maribel? That may be because Maribels event was a revival event of an early event for Nutakus aigis so chances are the drop rates weren't as high unlike this events where the missions are harder thus the drop rate is probably better than that of Maribels event, especially with the 90/12 map where she is a 100% drop.
Or it could have simply been the sting of RNG that makes it feel that way.