Mercari, chargebacks, banning, and possible lack of a refund

[Celestial3]

Hi! I ordered something through Mercari, and after poking the seller a bit through cancelling and backing out (because I still wanted it, but gave up on them shipping it, but then regretted trying to cancel it), they say they shipped it. It's been a week, and it hasn't been received by USPS. Mercari states I can cancel by the 23rd of this month, but their online support says I can cancel on the first of May. I'm tempted to file a chargeback since I paid with PayPal, but Mercari will ban my account if I do so. I'm worried about the chargeback being denied, being banned from Mercari, then not getting my package. In that case, I'm worried I wouldn't be able to do anything about it because I probably can't open a case or anything if my account is closed. If it arrives, I already bought a replacement for it. If my account is closed, I'm worried I won't be able to return it. From my understanding, Mercari's new TOS would allow me to return it if it did arrive. I spent a lot of money on this, and would like to get it back asap due to life circumstances. Any advice?

[Celestial3]

Giving more info I completely forgot about until now-- here's some screenshots of when it shipped, and USPS' lack of an update on it. The USPS screenshot says they got the label on the day that I bought it.

[removed]

The shipping says it's shipped through USPS Priority Mail, and is only 2 pounds. Given that it's a Meta Quest 2, I think the weight is listed as incorrect too. I know Mercari's online support is terrible, so I called and they said they could cancel it on the first. They also said they'd poke the seller, but nothing's happened. I've also messaged the seller a few times, and I've gotten no responses at all.

Thanks for any help I may be able to get,

Epsilon [Removed] (F.K.A. Katerina [Removed])