Coles coffee has become weaker over time even if I select the strongest setting so I've been experimenting with my own recipe. 1 shot of macchiato and a medium cappuccino in large cup. Regular strength on both. If you go too strong it becomes bitter.
I stopped drinking caffeine but had a few cheeky 711 coffees a few years agoโฆ it is weirdly acidic with a note of rubber. Not awful but definitely a bit acid on the stomach. And seemed very caffeinated.