Not blossom end rot.
I should have specified....it is literally the tip end of the swuash shrivellin up....wrinkly....gets soft and wrinkly.
I ate the big one after cutting the arinkly tip off.
Not rotten at all..just shriveling.
Nope. It’s blossom end rot. I guarantee it. The squash can get mature and still get it. That’s how the squash, big or small, reacts to a lack of calcium.