I am grateful for the exceptional effort you have put in to help me understand the topic. However, I believe what you said is correct; I think it's PWM mode 14, not 15. In my application, ICR1 controls the frequency (top), and OCR1A is used to change the duty cycle. I've always used it this way, so I may have expressed the mode incorrectly, and for that, I apologize. Still, I believe the upper limit for the frequency is 8 MHz.
I have read that when using very high frequencies, the execution of commands like delay in the application can be disrupted. Could you please confirm if there would be any issue with using this PWM frequency generation in the software I use to drive a MOSFET at such high speeds?
Thank you once again for your support and effort.