Would liposuction of the abdomen and flanks make my butt smaller too? Not happy about this.

Without photos- it's challenging to give a good answer. As far as i know- there is no major relationship between your abdominal wall fat and your buttock. Your options for a better buttocks are: muscle exercises that increase the size of your gluteal muscles for example- walking lunges. My preferred method for buttock gluteal enhancement is gluteal implants.

Sorry about your dilemma, but I am not sure how your butt could look smaller after lipo of your abdomen. If anything it should look a bit more prominent because of your flatter stomach. Weight loss or certain exercise may also be the culprit. Check with your surgeon and trainer!

My guess is that your opinion of your buttock is more perceived and real. There's no reason why liposuction of the waist and abdomen will have any effect on the volume in the buttocks.

It would be very unusual for your butt to have changed if it was not liposuctioned. Your waist may have, and perhaps that is what you are appreciating.