actually, for lots of people, including me, it's been a game changer. I started it a couple of years ago, lost about 20lb without trying, never hungry, eat really well (just having a brownie with my coffee right now). I have increased energy, rarely ill and it solved my gut issues. Worth every penny to learn what foods work best for my body and how to combine them for maximum benefit.
If at any point in my yo yo dieting past you had said to me "you will lose your post menopausal belly fat, wear size 8 jeans, eat what you want, never feel hungry, don't have to think about calories ever again, but it might cost you £24.99 a month" I would have bitten your hand off to sign up. As it is, there is now a £9.99 monthly option once you finish the testing / lessons period. Not everyone feels the need to keep using the app once they finish the programme so it costs them nothing, some people continue to log, others just use the app for the recipes and to find out what a "new" food might score. After 2yrs I can pretty accurately guess what anything would score for me, I just use the app for recipes and inspiration.
It doesn't seem to have taken off among MNetters like Ozempic clearly has, but there are lots of FB support groups. It doesn't work for everyone - I have friends who really couldn't be arsed to log their food in order to see the impact and one who has a disordered relationship with food anyway and just ate her weight in the foods that were good for her and put on weight.
It only works if you take the the process seriously and change your eating habits, but it is a 4month, structured, programme, to work through that process.