Otherwise how does a non-kyc crypto card makes sense with a custodial wallet and what triggers the service provider issuer to freeze your card or crypto if they don't know who you are to begin with

Yeah ! They don't know who you are but so far you're using their service they own your coin and can freeze it at anytime..
This makes them custodial over your funds as well so far they hold they for you and it's even much more easier to scam you if it's a fake provider or deliberate actions because you have nothing to show for , nothing tied you your account other than whatever they offer you..
They can also be decentralised, is not all that are like this.
Lastly, their service maybe regulated and if they notice any suspicious activity your account could be freeze anyways and you could have a low chance of recovery since you don't want to reveal your identity in the first place..
All these are stated on their TOS. Although some may state they don't keep any logs of users or state the only time your data will be shared would be when higher authority requests for it.
The TOS gives better clarity on every services offering on how they operate and thus includes if such service is Custodial or non-custodial.
Okay can you list which crypto debit cards use non-custodial wallets and which one would you choose?