Can't link a new Twitch account due to having deleted the already linked one without unlinking it

edit: for posterity

Bungie Account Name - oxyJinn#9889
Platform - Steam
Description of Issue - Cannot unlink deleted/nonexistant Twitch account from Bungie account
Rough Date and Time of issue - The account was deleted roughly a year ago or so
Repro steps - Account settings, connections, unlink twitch account, get "ErrorCannotLoadLinkedCredential"
LINKS: https://imgur.com/nG6PppU
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Hi there!

I used to have a Twitch account that was linked to my Bungie account
I had that old Twitch account deleted a bit ago, and forgot to unlink it from my Bungie account
I can't link my new account to my Bungie account, since it is already linked to a nonexistant account!

I have spoken to Twitch support and they weren't able to help; We tried unlinking through an incognito browser, no extensions, force recache what have you, the representative "performed some changes regarding your accounts connections" and it still didn't work, all concluding with the error message:
  Authentication Error
  Unlinking has failed because you signed into a different external account than the one you have linked. We cannot unlink your external account unless you sign into the correct account.

Then according to the Twitch representative we have hit a dead end and this issue was to be moved here.
My feeling is that my Bungie account is linked to a specific internal identifier for that deleted Twitch account, which can't be recovered by the Twitch support team. It would be helpful to get it so that I can forward it to Twitch and see what we can do. I would really appreciate any kind of support here.

Please let's cooperate on this, I just want to claim the twitch drops that I had already completed (both server slam and launch day)!