It’s a fair ask for wallets to support legacy key phrases. Daedalus already supports that.
The issue you’re having however is that you’re using a different wallet, like Atomic or Exodus and these wallets (according to your post, not making any claims here) allow you to stake ADA and in doing so, they also take the 2 ADA deposit, but when you choose to get your keyphrase so you can restore the wallet somewhere else, they only give you the old Byron keyphrase and/or they don’t let you “undelegate”.
If this is true, then this is an issue with those wallets. Allow me to explain:
- As noted earlier by Zyroxa, Byron addresses can’t delegate. So having the keys to a Byron wallet won’t support undelegating that wallet, the Byron address wallet was never delegated to begin with.
- In order for these wallets (these 3rd party wallets) to delegate to begin with, they must have at some point in time, issued a Shelley wallet and used that to delegate. It’s possible the wallet they issued to delegate on the backend is their own wallet and they only reflect rewards by depositing directly to your Byron legacy wallet. In which case, you never actually paid the 2 ADA deposit to delegate, rather they did, and there’s nothing to solve here. I’ve seen some platforms do this, especially some shoddy exchanges.
- In case they indeed created a Shelley wallet for you, is it possible you simply just need to update your keys again from these “wallets”. So perhaps you had the keys for the old Byron address before the wallet moved your Cardano wallet to a Shelley wallet and you haven’t pulled the keys after that happened so you’re trying to use the old Byron wallet keys instead of the new Shelley wallet keys?
- Similar to the point above, if they indeed upgraded your wallet to a Shelley wallet but still only show you the Byron wallet keyphrase even if you ask for the keyphrase again, then this is a bug in that wallet and should be reported to those developers respectively. They should give you the correct keyphrase.
This all goes back to the first point though, Byron address simply cannot delegate so something is going on outside of that. Either the wallet providers have a backend Shelley address that they use for everyone and as a result maybe you never deposited the 2 ADA (at least not in the sense that the Cardano protocol has claim to it), or they are simply showing you the wrong keyphrase and you need to pull the keyphrase again or ask them for support.
It’s also entirely possible they have their own Shelley wallets in the backend but still “charge” you X amount of ADA to delegate… this would be a fee outside of the control of the Cardano protocol itself and is entirely dependent on the wallet implementation., i.e., nothing to do with Cardano’s ability to support this.
Hope this helps. The main point I want to come across here is that you should probably check with the wallet itself and see if you can pull the correct key phrase for the Shelley Address. If you can’t do that, then it’s probably worth contacting the wallet’s support for help.