What info do you have to suggest the error message isn't accurate. Have you checked that your app does still have access and scopes required to make that call?
You've not given us much to work with here so the more context the better.
A simple postman script shows me the error:
Seeing the error doesn't mean that it's not unexpected.
I would make a bold assumption here that your app was making outdated calls to a long deprecated api version so could have been disabled. Though that's not the only reason why you might see that so best not to jump to conclusions. What's the request ID returned in the headers from a very recent call?
There is no request ID in the header from the postman example above.
It works again when I create a new app and use the new credentials from the new app.
It is due to shopify blocking the access for my old app?