Obviously you've been pushed to do this.
Been seeing this for years with CEXs, and wallets. It was just a matter of time. #Bitcoin is NOT compatible with fiat, you can't marry the two. Self-custody is a pillar of the Bitcoin ethos, and its eco-system, as well as P2P TXing.
Many of these services try to bridge the gap, there is no gap, there's an option to be taken. Opt out of fiat, or don't. It's a hard truth.
I understand the valuable service you guys provide, but it's important to consider that as the lightning experience improves over time, keeping custody of users' funds is not the way to go - decentralisation of control is a way to cover yourselves.
The separation of money and state is a fight. To them, you're collateral.