You can trademark a style, you can't copyright it. IANAL but that is what my corporate IP compliance training tells me. As long as am regurgitating non legal advice, I suspect half mona lisa half starry night might be considered a transformtive work. If a single human artist painted both perfectly onto the same canvas it could be construed as a statement about changes in the culture between the two contexts, so if you do it with Photoshop, it might very well get ruled the same way.

As for the morality of it? I don't like the idea of copilot replacing me, but I don't think it was wrong to make it. I'll eventually have to retrain myself to retrain copilot models I suppose. Or we'll have to decide to care for each other as we all go unemployed.