Custom app (store transfer disable) and custom app with store front api

[Sajjad1]

We have some confusion related apps on shopify.
(1) Why disable store transfer permission?
- currently we have make one custom app on shopify partner dashboard. we are install this app on any store then it will be transfer disabled. we have not done any code on the app right now just make app and install one store. There is show one popup like (https://prnt.sc/cWaN-UO48nEx) on the install app on any store. why store was transfer disable on blank custom app install?

(2) Checkout payment process with storefront api.
- we are using grapghql app on our store and storefront api for checkout process. we have done with create checkout and update shipping methods. But, now we are used "checkoutCompleteWithTokenizedPaymentV3" and they will be generated payment id and return payment id but order is placed on abounded checkout with error (https://prnt.sc/8BOvt5zcdrRm, https://prnt.sc/-xyMzzXPH09,- https://prnt.sc/z3-Fp_S-xU38), we are VAULT token generate from "https:/elb.deposit.shopifycs.com/sessions". why order is not place with payments.

Reference URL: https://shopify.dev/api/storefront/2022-04/mutations/checkoutCompleteWithTokenizedPaymentV3
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As well as we are used "checkoutCompleteWithCreditCard" this graphql api but this is getting error like https://prnt.sc/AWkQ5oeL3mcP
This is on default grapghql app but same thing we are used custom app for this graphql it is not working properly.

if we can use custom app with store front api, then it is possible to checkout api with payment?

Can you please guide me above points what we are make wrong here.

Thanks,
sajjad