From the looks of it, you might have a fastener that missed a hole and is trapped
under the panel pushing it out when the sun warms the panel.
What do you mean "again" ? Is it the same car, same panel and has it been replaced already ?
I had these same two rear quarter plastic panels warp like this, but this was on the 2020 Bolt and in a different city in Fresno CA. It showed up about 20 months into my lease ownership. I didn’t get these replaced, because I didn’t want to pay, and the dealership wouldn’t honor a replacement under warranty yet they didn’t have a good reason why it happened. Blamed me for it but also didn’t have a reason. GM charged me about $90 during the lease return process.
This time, this is on the 2023 Bolt EV (seems to be the exact same parts as shared with the 2020 Bolt) in San Francisco, CA (much cooler climate than Fresno) and only 2 months in. I can’t imagine foul play (different city, different neighbors), and the car only gets driven 500mi per month around the city mostly. At two months old and 1200 miles, I’m very puzzled.