Idler pulley

You need a real live person to look at that, but it is a possibility. The squeal is caused by the belt sliding across a pulley as it goes around it, and that is caused by that pulley or the one right before is tipped or turned. Most tension-er pulleys are on a spring-loaded arm, and its pivot point can become worn, allowing that pulley to tip. Less commonly, an idler puller that simply runs on a bearing can become worn.

There are a few things you can look for. First, sight down from straight above the belt where it goes around the highest pulleys, and continue looking down to the lower pulleys. The belt should be in such a straight line that you should not see it peeking out on the lower pulleys. If you do find a pulley where the belt is off-center, look for the area where paint is worn off that pulley. Most pulleys are painted black. The area where the paint has worn off will be silver and should be totally covered by the belt. If that silver area is wider than the belt, the belt has moved off-center, and that pulley and the one right before it are suspect.

It is also not uncommon for the spring-loaded tension-er puller to become rusted tight and fail to put the belt under proper tension. To identify that, tug on the belt fairly hard and you should see the tension-er move. What is important is it must retract when you let go and pull the belt tight again. (Do that with the engine not running!)

Here is an article that offers more information:

https://www.2carpros.com/articles/car-squeaking-noise

You could also have some grease on one or more of the pulleys, causing the belt to slip and squeal. Personally, I would take the belt off and use an old towel to clean off the pulleys. Then put the belt back on and see how it does. I am also attaching the belt routing diagram, in case your car does not have it under the hood any more.