Changing the default Color Theme in 7.1 (2023)

I've noticed today that I can no longer change a website's default colour theme on the mobile app. It seems that this is no longer an option after reading up and talking to SQS Support.

https://support.squarespace.com/hc/en-us/articles/205815278-Changing-colors#toc-default-color-themes

I can't understand why this is now effectively baked in to the template, and since you can't change a 7.1 template without building a new website, this seems unbelievable to me. 

I guess I'm just complaining, and need to change my process, but switching a website from a light to a dark design now will involve taking the default "Light 1" theme and changing every single colour option individually. Or maybe turning the colour pallete upside down would work? Any good ideas? Thanks.