Ok I just did a quick weight test and the difference is massive!
The store bought beans are marked 6/7 darkness and gave me close to 60 ml of volume.
The subscription without marking gave me <50 ml for the same weight. That’s allmost a 20 % difference in weight even though they look very similar!
I’ll do another test with an exact number of beans to confirm, but I’ve learned a lot already. Maybe my 1:3,5 ratio wasn’t half bad after all and what to actually expect from such a light roast.