This is called parsing - your brain processing the speech sounds into meaning. That feeling of suddenly realizing what was said is your brain needing a little extra time to parse.

This can happen for lots of reasons. One time my sister in law was so grumpy that my brain struggled to parse what she was saying because the tone and words were so mismatched.

If I have a dollar every time this happens I think I'd be good for groceries

What?

OP has a slow cache, might need to upgrade hardware

Autistic people:

This happens to everyone. It happens because your brain registers the other person saying something before it actually understands what is being said. And when most people don't know what someone said, they ask, "what?" without even thinking. Source: my intro to psych textbook.

This is why I pause after someone says "What?"

Then they look at me puzzled when I don't repeat it.

Quick solution: when you don’t understand what someone just said, wait a few seconds before asking what. Often, your brain will fill in the gap given a second to catch up.

That's why, if someone responds with what?, I usually wait for a few seconds. It usually resolves the question on its own.

Forgot to press the turbo button again 😹

Nah, my what is for the last 2 words, not for the entire monologue to start over

Yeah, you gotta let it load sometimes

This happens quite often to me, especially when tired. I'm assuming that for me it's mostly autism related. That being said, I've noticed that many non-autistic people also have this happen every now and then., it just happens more for me.

Might be some form of APD, a lot of my family members have it (myself included XD)

Yea my brain is like a Kafka system

GET IN THE FUCKIN QUEUE

What?

This is me with the owl from OoT

a '90s* dell computer