I'm not sure if this is also present in EU law but in German law online services like web shops and in-app purchases require very specific wording for any butto

I'm not sure if this is also present in EU law but in German law online services like web shops and in-app purchases require very specific wording for any button that has the user commit to a payment or purchase. The recommended wording (which you're allowed to deviate from but is not recommended unless you know what you're doing) in German is "Zahlungspflichtig bestellen", which means something like "Order with obligation to pay". The label "Kaufen" ("Purchase") was deemed insufficient. Note that this also requires the user to be informed about what they will have to pay before they click the button. No bullshit surprise charges or hidden fees, mostly.