Is the cocoa pod deprecated ? + missing versions

[mostafaberg]

Today I noticed that pod install throws this error:

[!] CocoaPods could not find compatible versions for pod "VPNApplicationSDK":
  In Podfile:
    VPNApplicationSDK (~> 4.0.3)

None of your spec sources contain a spec satisfying the dependency: `VPNApplicationSDK (~> 4.0.3)`.

You have either:
 * mistyped the name or version.
 * not added the source repo that hosts the Podspec to your Podfile.

When I run pod trunk info VPNApplicationSDK I get the following output:

VPNApplicationSDK
    - Versions:
      - 3.1.4 (2020-06-30 10:07:24 UTC)
      - 3.1.5 (2020-09-29 09:29:02 UTC)
      - 3.1.6 (2020-11-10 15:51:12 UTC)
      - 3.1.7 (2020-12-01 08:46:49 UTC)
      - 3.1.8 (2020-12-24 16:26:56 UTC)
      - 3.1.9 (2021-01-18 16:58:15 UTC)
    - Owners:
      - ***redacted***

I have a few questions: 1- Where did 4.0.3 go is this a bug? 2- The cocoapod is now deprecated, what is the alternative ? I'm not finding any replacement ?