Error:
Your app currently targets API level 30 and must target It least API level 31 to ensure it is built on the latest APIs optimized for security and performance. Change your app's target API level to at least 31)
Possible Remedy:
https://support.google.com/googleplay/android-developer/answer/11926878?hl=en
To help ease the transition, we are delaying the enforcement deadline for app discoverability from November 1, 2022 to January 31, 2023. You can continue to request an extension if you need more time to update your app to target API level 31 or above by submitting an extension request for your app to continue being discoverable to all Google Play users until May 1, 2023. Check your Play Console Inbox Messages for links to each of your app’s extension forms.
Question:
How to request for extension? I couldn't find the "links to each of your app’s extension forms"
According to the FAQ at the bottom of the page you cited:
Other than waiting for Google to send you the info, you could try and update the targetsdkVersion to at least 31.
At the manifest, check that targetapi is at least 31. Check for bugs (if anything has been deprecated), sign and upload.
Edit: App updates are not available for APIs below 31 as of November 2nd 2022.