Hi , @geenee
According to your description, you want to update the Date column when the [Approval Status] column changed to the "Approved":

This is my flow:

(1)The trigger , you need to set the trigger condition in the setting of the trigger.

@equals( triggerOutputs()?['body/ApprovalStatus/Value'] ,'Approved')
(2)The "Get changes" action:

sub(int(triggerOutputs()?['body/{VersionNumber}']),1)
For this , you can refer to :
Power Automate: Start a Flow from a column change – Ben Prins
(3)The condition and the update item action:

formatDateTime(utcNow(),'yyyy-MM-dd')
And you need to replace your internal columnname in your side.
If this reply can help you , you can click mark this reply as solution (Accept solution) which can help more people, thanks in advance!
Best Regards,
Yueyun Zhang