Squealing sound when I start car

Your serpentine belt is squealing on the alternator. One of two possible causes for this. Either your serpentine belt is worn out or your tensioner pulley is not doing it's job (tensioning the serpentine belt). The pulley can wear out over time allowing the belt to slip a little. At startup there is a heavy load placed on your alternator, which causes it to squeal on the belt. Once the belt is warmed up, it can grab a little better, plus the demand on the alternator will have subsided some, which will allow it to stop squealing. Replace the belt first, as I would put a much higher probability on this being the problem (plus it's a lot easier and cheaper to replace).

I drive a 2017 Nissan Rogue and was having the "squealing problem" in the AM when I start my car. Also, I live in Austin, TX where the temps are pretty chill in winter months.

I took my vehicle to Nissan dealership express service lane and here was the result: 1) Opened hood of car and identified Serpentine belt 2) Did a visual inspection and determined that belt was not not frayed or loose Conclusion: No real issue if this happens only we the car is started first thing in the AM. Since the Serpentine Belt works with alternator to supply electricity to the car, indicator light will activate on panel if there is ever a serious issue.

Could be a problem where starter drive and flywheel teeth are not properly engaging. This would require a starter replacement. Sounds like your car is still under warranty and the dealership is trying to avoid the real problem.