I have a 2015 Nissan Altima. After I bought the car, I learned these cars have transmission problems but since I had a lifetime warranty on engine/transmission I didn't worry about it at all. After having the car for almost 2 years, my car would lose power while driving the car. It wouldn't all go away, some power stayed which allowed the car to still drive daily, but it became annoying. It was similar to how a manual transmission would be in 5th gear going about 15mph. Very similar to that feeling when this would happen.
After about a month, I noticed my brake lights would stay on sometimes after I turned the car off. All I had to do to make them go off was tap the break pedal. My dad said probably the brake light switch. I ignored the problem for another month for various reasons. But doing so allowed me to notice some other things. I never thought the brake lights could affect the transmission, but what I noticed while driving the car for extended periods is that the Vehicle Dynamic Control light would come on when the transmission would act up. It looked just like the traction control light, but wasn't that light because that light was right next to it so I knew it had to be something else which I now know is the Vehicle Stability Control or maybe VDC (might be the same thing?). The light wouldn't always come on when the transmission would lose it's power, only if I drove it for 15-20 min at a time it would do it.
What I then learned was that if I tapped the break a certain way, it would fix the problem instantly and my power would come back and car ran as normal. So now I am almost certain it is only the brake light switch. I am going to change it today, so I may not need any advice haha, but if not, what else could it be do you think?