Is it just Oxidation?

Hello! I’m having a problem with my mushroom grow — the strain is Yellow Umbo. I had to leave the house for a while, and when I came back, I was surprised to see that they had grown. However, it looks like they didn’t get enough fresh air exchange. As a result, the mushrooms are a bit deformed, and some of the caps didn’t fully open. There’s also quite a bit of oxidation where I touched or cut them, though the inside still looks fine.

What do you think?

Hello! Your shrooms are fine, there's nothing to worry about. Now dry them thoroughly.

Yes, bruises appear due to oxidation, which is a normal reaction.

As for the caps, some of them are already open – you can see the torn veil under the cap. Some are closed, because they just needed more time to grow. It's okay if there are mushrooms at different stages of growth in one flush. In fact, you need opened caps if you're going to make spore prints or spore swabs. But it's fine to harvest shrooms with closed caps or just before they open.