I’ve just setup live on square and implemented SCA. It is working pretty smooth in the sandbox but when I implemented on Live website it didn’t asked for SCA on card which is SCA enabled and of EU. It just straight away verified the payment and completed it without asking for 3d secure code.
In production, it’s up to the customer’s bank whether or not to request verification. Some banks (as far as I know) aren’t even requiring it yet in the EU, while others are. If the customer’s bank is requiring it, it still may not happen every single time.