When attempting to run a task within On Demand Migration (ODM) the following error will be returned if MFA is being forced on the admin account(s).
AADSTS50076: Due to a configuration change made by your administrator, or because you moved to a new location, you must use multi-factor authentication to access
ODM does not support MFA being applied to the admin accounts used for the source and target connections.
Check the source and target admin accounts to verify MFA is not applied either directly on the account itself or being assigned through a Conditional Access policy.
If the source and target Office 365 migration admin accounts have Multi-Factor Authentication disabled, then that indicates one or both of those accounts (or the account used to grant consent if a different account was used grant consents) are not excluded from some Office 365 Conditional access policies that assign/enable MFA.