Hello @Andrew Piskai
I'm glad that you were able to resolve your issue and thank you for confirming the solution over teams.
Since the Microsoft Q&A community has a policy that "The question author cannot accept their own answer. They can only accept answers by others ", I'll repost your solution in case you'd like to "Accept " the answer.
Issue: I'm unable to sign into portal.azure.com [Error code: AADSTS5000224].
Solution: Azure was defaulting to one of the directories that you were deleted, so you had to manually tell it to go to a different one by giving a hint at the end of the URL....
portal.azure.com kept going to a deleted tenant
portal.azure.com/alternatetenant.onmicrosoft.com allowed you to go to one of the other ones so you could get back to the directory screen. So that the issue got resolved.
If you have any other questions or are still running into more issues, please let me know. Thank you again for your time and patience throughout this issue.
Please remember to "Accept Answer" if any answer/reply helped, so that others in the community facing similar issues can easily find the solution.