Hi - any insight as to why my leaves are yellow? :/ It's Zucchini, mint, yellow squash, & tomatoes

Plants look ok. It is normal for older leaves to yellow and fall off as plant develops.

Agreed.
Maybe some gentle fertilizing if you aren't doing any.

@farmerdill God I think you! I actually did not realize this was normal! @sallyg And thank you! I am actually not fertilizing, It will definitely do gentle fertilizing