They're not lying but rather likely didn't know about the per-app exploit protection compatibility mode. They narrowed it down to secure app spawning needing to be disabled. Now they know what to do when an app doesn't work on GrapheneOS.
You can help by upvoting the update they posted with the solution:
They did actually and knowingly lie. Because I guarantee that they had no way to affirmatively know that PayPal themselves had done anything to their code. They didn't see no ChangeLog and they didn't see no Release Notes about it. They didn't read any news from the app developers. They jumped to conclusions about malice when it was actually incompetence and ignorance, much like their own.
They could've simply neutrally stated that: "PayPal crashes when I try and run it under GrapheneOS" and that would be a true statement without assigning blame or malice. But, not knowing PayPal was innocence, they chose to assign malice to them instead. That's a choice. That is rash judgement and calumny.
You can help by upvoting the update they posted with the solution:
https://news.ycombinator.com/item?id=49462575