when using more than one email within "Assigned to", and the approval type is "Everyone must approve", the firs one to get the approval it's available to approve the other one get the approval but when opens the email says " You did your part, no further input is needed from you at this time", and the flow keeps running on "Start and wait for an approval" step
Try removing and re-adding the approval step. That's acting like its set for "First to approve" rather than "Everyone must Approve".
I think you'll need to open a support ticket with Microsoft then. That is definitely not the normal behavior.
Follow the steps in this documentation.