There is a shortage Mac Minis and Mac Studios, especially those with larger RAM configurations. Sometimes Apple stops producing the current models when new models are around the corner. Or, this could just be a result of demand and the global RAM shortage. Either way, there are a few indications that the Mac Studio models featuring the M5 Max and M5 Ultra chips could be announced in June (and released shortly after) with the updated Mac Minis likely coming in the fall.