Hello @Aishwary Bohra , the ABTechLab.in
domain is still configured as a custom domain name in the abtechlab.onmicrosoft.com
tenant: https://login.microsoftonline.com/ABTechLab.in/v2.0/.well-known/openid-configuration. Ensure domain is deleted or gets deleted trough a force operation. For further assistance create an Azure Support Request ensuring Advanced diagnostic collection is enabled and request it to be assigned to Alfredo Revilla, that's me :)
Let us know if you need additional assistance. If the answer was helpful, please accept it and rate it so that others facing a similar issue can easily find a solution.