Locally, both Pepsi and Coke have both gone bananas with seemingly endless new sugar-free flavours recently and all of them are terrible

I've not seen many of those lately, MtnDew seems to be flying off the handle around me. I have a hunch it's in response to supply chain instabilities. They want to avoid ever having all those empty shelves out there losing revenue so they're getting people used to drinking whatever soda-mcrib ingredients the market makes most available to them for cheapest.