Can Zombies stop dropping Tinkers' weaponry?

[atomic-cherry]

Modpack version
1.3.9.2

Issue
I've been having an issue with slowly increasing world lag. When I decide to go exploring, I realise what the culprit is when I stumble upon piles and piles of abandoned tinkers tools that dropped from dead zombies that can't despawn or be destroyed normally.

There are many more underground, too, which I can see with Botania's Spectator. (Yes, every one of those was a tinkers' tool.)

Normally the player would have to kill them for them to drop, but somehow the zombies are being killed without me there and just causing these endless pileups of item bloat. Long term, this would probably make the save unplayable without going out there and finding and manually deleting them.