Power Automate- trigger an approval flow from a change in a field

joelosi your trigger needs to be when an item or a file is modified and the first action is get changes for an item or a file (properties only). But because you are comparing the current version of the status column to the previous version you MUST turn on item version history in your List Settings  -> Versioning Settings

The Since field is where you add the expression to compare the current version with the previous one:

sub(int(triggerOutputs()?['body/{VersionNumber}']),1)

You need to check not only if the Status column has changed but also if the value is now Approved or Completed or whatever value you are using:

The status column in my list is a choice so if that's the same with you select Status Value, not Status, from the dynamaic content box:

Rob
Los Gallardos
Microsoft Power Automate Community Super User