blamester

So I didn't know where to post this as it's just an observation.
I was watching the Brussels one day race (on the GCN app which issis excellent) and thru out the race I could hear screeching which I thought was the whistle to notify the spectators the race was coming. But it was the brakes and I'm pretty sure it was hydraulic brakes. And it was all thru the peloton. For sure the winners brakes where screeching horribly.
I haven't used hydraulic brakes but if the pros are running them like that then wow. It was very wet but I thought that was the big benefit of hydraulic brakes. I could not have ridden the winners bike in that condition I would be too embarrassed.
I haven't heard anything like that in the big pro races or maybe a little. This was a pro am kind of race.
So what was going on?