Remember the discord leak. In it, Phil admitted that Rumple had successfully charged back like 300 dollars from him. So I think he isn't lying when he says that people charge back lots of tips, but he may be exaggerating how many chargebacks happen.
But I'm pretty sure he's not so dumb that he'd let his PayPal account go in the red, he's probably annoyed that he has to let 100 dollars or more stay still in his PayPal instead of going straight to sweaty men JPEGs.
His slightly different current circumstances have likely lead to this weird flip.
When Rumple was active and winning (among others who were probably winning chargebacks), Phil was heavy in debt and his paypigs were less consistent (stream tip goals were not hit, influxes of money came from near-monthly fundraisers). It was in Phil's interest at that time to lie about winning all chargebacks in order to deter them because he needed to do what he could to maintain a steady income with occasional spikes.
Now, Phil regularly hits tip goals and will frequently exceed them. Between OiC and Boone, he is getting massive monthly paychecks from Twitch that he memoryholes in any money conversation. I suspect Phil is getting an influx of chargebacks, but that he isn't losing them all. His choice to 'refund' on screen is dubious, but it seems to be connected to one account in particular, probably who regularly wins against him anyway. While other tips are suspect, he doesn't refund them immediately because he may have a chance to win those on challenge. As an added bonus, he now has a reason not to add them to to the tip goal, so the money is effectively 'hidden' and never mentioned again.
However, he is already making more than enough to balance out any chargebacks he actually loses, and if he uses the chargebacks to beg, he can probably balance them on the extra begging alone. Further, he has no other reason to beg now. So now, he is talking about losing chargebacks, and framing it like he is instantly losing the money when it is contested only because this is now the way he nets more money. Phil is always lying to some degree, and The Narrative is just whatever is going to result in more money in his pocket. An inexplicable shift like this is usually just because he sniffed out a better pile of truffles/money to pursue.
Imagine you are soo greedy, you empty your paypal EVERY DAY just so you can instantly spend it.
Even worse, Paypal charges him a fee for transferring it immediately. If he just waited, there's no fee. He wants that money so bad that he's willing to lose a small portion of it just to have it in his pocket right away.
