I see the article: API Deprecation at Shopify: 2021-04 Edition by Alex Bradley at Feb 17, 2021
And the documentation comments: https://shopify.dev/concepts/about-apis/versioning/private-apps
On April 1st, 2021, private apps will no longer have access to unsupported versions of the API (2019-04, 2019-07, 2019-10, 2020-01 and 2020-04). Requests from private apps that use deprecated behavior will no longer be supported, and will instead follow the same behavior as public apps.
We are working in the upgrades, to reach the most recent versions or at least the 2020-07 release but if we cannot reach the deadline, I want to understand: How this impact the apps that we have?
Our apps are public and available at Shopify store, we have merchants already using them. So we want to know if their access to use the apps will be notified as warnings or depending on the deprecated endpoints, the actual behavior will be different for each app depending on the endpoints they are using (If the some API endpoint is deprecated, the app will have errors, If not one endpoint is affected, the APP should still working but with alerts), this doubt is related to: https://shopify.dev/concepts/about-apis/versioning/private-apps article.
We understand the effort required to use the latest API versions: https://shopify.dev/concepts/about-apis/versioning/release-notes and we want to complete such requirements as soon as possible, but we want to understand the actual behavior with our apps and Shopify stores using the apps at April 1st, assuming that we have the 2020-04 API version.
Additionally we wanted to try first the https://shopify.dev/docs/hosted-payment-sdk approach, because it was recommended by Shopify. The main problem was that never was possible for us to recover the API keys to start a development using the Hosted payment solution (And then COVID-19 appears). We exhaust all our efforts to reach this goal, but at least 1.5 years were passed and we still waiting the credentials or some kind of support in order to start this development ASAP. As a result we are not using hosted payments SDK today.
Thank you in advance, we will be checking the forum to see your response.