Ive never had any issue like that to be honest, and I have been using FF literally daily for years. Most of my social circle are yucky apple product users so I haven’t even heard of this issue until now. Im sorry you and other people have it because tbh FF is basically perfect, at least for what I need it for
In my neck of the (american) woods, it usually is “free delivery! No fees if your meal is $15 or more!” according to their ads, but then they artifically raise the menu prices in the app. A meal might cost you $12 with tax at a burger place near me, but on ubereats / doordash that same meal is $19 because they raised the menu price. That way when you go to pay, it says there was “no extra fee”.