Persimmons were still quite green when I picked them, as the birds had already gotten to the ripe ones first.

They also have very thick skin compared to store bought persimmons, which might be a good think, as I only found superficial damage and just one bug near their weakest part around the calyx

Guavas on the other hand... let's just say I won't need any extra protein in my diet for a while

protein enriched

My brain: "Oh cool is this some new varietal... or... oh... oh god"

I wonder if this is why the persimmons seem different to you from the store?

American vs. Asian Persimmons: What’s the Difference?

It reminds me of an old joke:

Q: What's worse than finding a worm in your apple?
A: Finding half a worm.

It's my fault after all: If I hadn't taken a look, I'd have never known

Yeah, it could be that and it was definitely astringent when unripe. I can't confirm right now as this tree wasn't tagged, but I'll ask around to see if anyone knows