Approval not updating "Modified By" user

[priests123]

We have been experiencing the behaviour on SharePoint Online.

When a Approver user approves a SharePoint item (Document or page), the "Modified By" user does not update to the Approver user. Instead it remains as the user who last modified the document. When the Approver user approves the "Modified Date" does update to the time of approval. 

Here is another discussion about the same behaviour but it has no replies.

Does anyone know if this behaviour is by design or a bug in SharePoint?

Does anyone know if it is possible to capture this Approver user? For example through SharePoint REST

[#2]

If the approval date is modified, then the modified by should be updated with the approver user inmho so I would say this is a bug

[#3]

What I usually do is have it capture that information in a text column with "append changes to existing text" enabled with Power Automate - it creates a date/timestamped comment with the approver name and outcome. I have a write-up on how to do that in this article.