How do you delete items in "invisible" slots of shulkers with commands?

When you generate a shulker with stacked items that are supposed to be unstackable inside, then break it, the items separate, and while 27 of them remain visible, the other 37 items (provided that you generated a shulker with a single stack of tools) go into "invisible slots", where the player cannot access them, but still remain observable through NBT tags. If you have a lot more items in a shulker, having these broken "invisible slot" shulkers can put significant strain on a server, because the game renders all of these tools and their respective tags seperately.

Example of stacked shulker (use /give @p minecraft:purple_shulker_box{BlockEntityTag:{Items:[{id:"minecraft:diamond_pickaxe",Count:64b}]}})

After you break one of these shulkers in survival, they seperate like so:

While it may appear that there are only 27 normal diamond pickaxes inside the shulker, when running the command /data get entity @p directly after breaking it (placing it seems to normalize all the invisible slots) shows this (I wasn’t able to fit all of the output into the screencap):

With all this said, I’m trying to create a datapack that will modify these illegal shulkers so that the invisble items inside the shulker are destroyed, so that it won’t lag the server out so much, but I’m not sure how I can do this. Any ideas?