Same. I didn't know that I was PWM-sensitive until now, because I have been using OLED iPhones for years without any issues. But just a few days ago I bought an iPad Pro M4 11'' and the symptoms started right away, including eye discomfort, dizziness and even headaches. Also, a strange feeling of sleepiness and disconnection, making it really difficult to stay focused on the task at hand while using the iPad.
I did a lot of research and tried everything: switching true tone on/off, disabling ProMotion, trying light/dark modes, increasing brightness to 100% while reducing the white point, and so on. Unfortunately, nothing seemed to work, so I had to send it back. Such a shame, because it's a fantastic device and the screen is simply gorgeous, but it was completely unusable for me.
Now I'm trying to decide between the Air M2 11'' and the 13'' to replace my ancient iPad Air 2 🥲