Hello @KunalChadha
One of the impacts of that Deprecation notice was that OAuth 2.0 requests will no longer be pre-processed to fix invalid URLs in requests, including the removal of trailing slashes.
In your thread, I can see that you have such a trailing slash in your provided example request:
curl --location 'https://api.atlassian.com/ex/jira/{{Cloud Id}}/rest/api/3/issue/createmeta/?projectIds=10225&expand=projects.issuetypes.fields&issuetypeIds=10003' \
That extra forward slash after the word ‘createmeta’ and before the question mark should not be there, so first try removing it. It might be the fix, in your specific case.