Merry Christmas to me!! Just ordered likely my last camera, Canon 5D MK IV

About 10 years ago I bought a 5Dmklll as a retirement present for myself. That camera and my Rebel T2i gave me range from hiking in the rain to creating good images for my camera club. A year and a half ago I decided to do the mirrorless thing and bought a used Canon R6 with a 24-105 kit lens. Soon after that an RF 70-200 f4 and then an RF 100-500 f3.1-5.6. About 8 months ago I sold the mklll to a very greatfull young lady who wanted to get a full frame camera.

Mistake 1. Believing the mirrorless marketing hype claiming superior images.
Mistake 2. Investing in RF lenses when my EF glass was giving me great images through an adapter.
Mistake 3. Selling my mklll.
Mistake 4. Selling my mklll.

The grass isn't always greener on the other side of the hill and IQ of the next system is probably not going to be any better than what you are using.

That mkiv is a great camera and will serve you well for a long time to come. I wish I would have gone in that direction also.
Good luck, Jerry