Looks like SSAO2RenderingPipeline property .textureSamples has no effect in version 4.2. There are jaggies regardless number of samples (see image below). Version 4.1 provides almost no artifacts. There are no jaggies w/o ssao.
This is a repo: https://playground.babylonjs.com/#WGZLGJ#2101
Change the engine version to see how it changes.
Can I make something to remove the jaggies?