When Pippa first showed she had the ability to raid Mori, I had a few thoughts as to why Mori might be following her, but then it was revealed it's just because of it no longer being whitelist, so I put those thoughts away... but here we are, Mori clearly knowing about Pippa and even using her catchphrase correctly.
So my suspicion mainly lies with /vt/. Mori, as shown in her VA-11 HALL-A streams and the NSO stream, has an issue with egosurfing, but particularly on 4chan/imageboards. Given this, I suspect she lurks, possibly even posts there regularly, under the guise of being a fan.
With this in mind, her knowing about Pippa isn't really that strange at all. Pippa has a fairly large presence on /vt/, even outside of the phase connect community, mainly due to her content, and she and Mori have been connected via the "pink women" thing. From another angle, it's possible she became interested in her due to her content itself after seeing her on /vt/ - after all, Mori's blown several dogwhistles regarding being familiar with Ghost, so her having a casual knowledge of lolcows/internet metacommentary culture possibly drew her to Pippa as well. Given that unlike Fauna she outright referenced her intro, she has probably at least seen one of her streams, if not a handful. I'd be curious to learn more.
Art tax: