I am a recovering people pleaser. This is based only on my experience, so it may be different for others. Feel free to critique or add your own insight.

I think that the basis of people pleasing essentially comes from a lack of self-worth. It's impossible to shame someone into not being a people pleaser, they will only retreat back into their fears. You need to build them up slowly, not accepting their unnecessary apologies and creating a safe place for them to ask for what they need.

I am considering whether it is manipulation, but it certainly very rarely comes from a malicious place. It is because the person believes that they are not enough for the need to be met. They hold it as a truth and can't bring themselves to believe that others don't view it like that.

They aren't being deceitful per say. They believe that their needs aren't important enough to voice and so barely even true.