Just take it to the dealer, and they will fix it. Likely replace your brakes or pads under warranty. Many 4Runners are being held right now for brake issues. Just take it in. They will fix it.
My trd pro does the same thing when I leave the house in the morning sometimes. It’s less annoying than how slow the dealerships service department is though, so I haven’t messed with it yet.
I took my 2025 New Sr5 4 Runner to the dealership and I was told that they had to validate and video the brake issues to Toyota. I will have to drop it off and leave it for the day so they can document everything and then come back at a later time to resolve the issue.
Mine is a few weeks old, still under 1k, still on the temp tag, got the squeal this morning. I'm driving from nj to tx and was pulled over to sleep a few hours in va. this is 8:30 am, truck is cold, environment is not raining but overcast and slight morning dew, cool wooded shaded area. light brake pedal in reverse.