Hi @opsengineer,
You can create a recurrence Flow runs every hours. Then Get File properties of the target, after that, create these conditions:
-Modified by is equal to Created by
-Modified is greater than addHours(UtcNow(),-1)
If it is true, post message into the channel.

Best Regards,
Community Support Team _ Lin Tu
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.