Could it be the cork oak, Quercus suber?

What does the bark look like? And the acorn?

ETA: Sorry, you want to know the oak tree problem, not oak tree.

Location is important to get help here. Could be oak wilt or perhaps branch damage,

Thanks for the feedback. The location is the Bay Area: Oakland, California.

Here are a few more picture of the bark and the tree. Should I cut the whole branch, or is there a remedy? I am mostly worried that it will also affect the other oak trees around.

Thanks, Jordan. Do you think the whole branch needs to be cut down?

Depends on what you mean by it. The bark looks like from other trees, and these are old trees.

I would tend to say no. What do I have to look for? Here are some close-ups:

This is for the affected branch. Thanks for all your help! I hope I can save this tree.

Thank you Jordan. I will do this tomorrow. Let's see what I can find out