Hi Gabe,
Below you can see screenshots of my performance settings in Photo and Designer respectively.
To know which GPU is being used my computer I use the Monitor (also attached screenshot). As you can see, Affinity apps appear as not using high-performance GPUs. I also look at About this mac, where it usually appears on the screen that GPU is being used. And I also take a look at System Report, in the Graphics / Screens section, where the use of GPUs also appears.
I have also noticed that with Final Cut, Motion, and iMovie this problem does not exist. Attachment screenshot.
If you need more information from me ask me. Any idea what may be happening?
A greeting and thank you very much for the help.