Hi Toshant,
One way is via the developer changelogs.
https://shopify.dev/changelog?filter=api
Another way is looking at the release notes for each API version
https://shopify.dev/docs/api/release-notes
If your App is a public app then you should get warnings in the App Health Report from your “Apps” Dashboard from your partner account.
if its a private app you can subscribe to updates via the App Contact Information.
And remember Shopify releases API Versions each quarter. 01, 04, 07, 10. Its your responsibility as developer to ensure that your apps don’t make deprecated calls.
Cheers,
Gary