Why does my Canon EF 70-200mm f/2.8L IS III USM lens produce more chromatic aberration with a 1.4x extender than my old EF 70-200mm f/4L USM?

I've been experimenting with different lenses and extenders for my photography projects, and I've come to a realization that's been bothering me. It seems like my Canon EF 70-200mm f/2.8L IS III USM lens, which I thought was one of the best out there, is actually producing more chromatic aberration when paired with a 1.4x extender than my older EF 70-200mm f/4L USM lens. Now, I know what you're thinking - the f/2.8 should be better in every way, but hear me out. I've been shooting with both lenses in similar conditions, and the difference is noticeable. I'm starting to think that maybe the newer lens is just more prone to CA, or maybe it's the way the extender interacts with the lens. I've tried adjusting my shooting technique, using different apertures and focal lengths, but the result is the same. Has anyone else experienced this issue? Am I just doing something wrong, or is this a real problem with the lens? I've also noticed that the bokeh on the f/2.8 lens is not as smooth as I expected, especially when compared to the older lens. I'm starting to wonder if I made a mistake upgrading to the newer lens. Maybe I'm just not used to the way it handles, but it's definitely got me scratching my head. I'd love to hear from some of you experts out there and get your take on this.