First you should read this for an understanding what controls and anchors actually are and how they are used:
You got controls in the game.
https://wiki.esoui.com/Controls
Like a label for text or a background or a texture, a chekcbox etc.
Each needs anchors to "anchor themselves" to another control of the UI.
Some need more anchors to e.g. anchor to the left and the right of the inventory = 2 anchors -> maximize the visible size.
https://wiki.esoui.com/Control:SetAnchor
It's not PP which got the huge amount of anchors. PP maybe just adds a few anchors which will result in a sum > than the games allowed maximum value in a defined time period.
But as PP changes the inventory and there are a lot of controls in the inventory (icons, rows, etc.) it might be thjat PP alone re-anchors the exisitng controls which will make PP the one addon causing the "too many anchors" (in a time period) processed error message.
It's all addons together as a sum which causes the problem here.
control:ClearAnchors() is a function which will remove the anchors and then these controls will be floating around without actually being anchored to something else anymore. The next time the UI refreshes e.g. the controls they will be in a wrong state, size or position.
So anchors are needed to kept up2date and you are not able to remove them unless the controls WON't resize, hide or be moved at all.
You can use addons like AnchorAway to suppress the error message but a real solution would only be to disable addons or check which ones really produce a lot new controls (or re-anchor a lot exisitng ones) and thus anchors as well, and tell the dev to maybe delay the creation somehow in oder to make the game not spam that error message.
But this is hard to track as there are not functions to find the addons or amounts of anchors.