Yes. Well, kinda. You can maintain the resolution, but you'll be losing information regardless.
But that's what's needed here. The current image contains a lot of compression artifacts, which are extraneous information, and that's what the upscaler seems to want to enhance. Wipe that information out and you're left with the rough structure, which is what we actually want enhanced.
AI is gonna introduce new information to input new resolution from nowhere either which way, so we're just priming and massaging and optimizing our input so as to remove any obstructions that might trip up the AI enhancer. But yes you're right, ideally the enhancer should know how to take into account compression artifacts but this one doesn't.
But that's what's needed here. The current image contains a lot of compression artifacts, which are extraneous information, and that's what the upscaler seems to want to enhance. Wipe that information out and you're left with the rough structure, which is what we actually want enhanced.