I have PS 8.0.4 on PHP 8.1, and I will write what I performed. I checked the rights of the directories. They are appropriate. In general, I checked the condition in Advanced → Information and I see no errors. As I used all ideas, I installed a clean installation of PS 8.0.4 in the domain subdirectory and there are no problems uploading product image files.
In view of the above, what might be the ideas for upload image problems? It seems that the complication is with the PS instance itself, not the VPS (on control CyberPanel).
What ideas do you have?