It sounds like you've already done this, but have you read about when Candy Japan was hit by massive fraud and how they solved it? (TLDR: don't let fraudsters know the card was declined, make it look valid)

https://www.candyjapan.com/behind-the-scenes/candy-japan-hit...

https://www.candyjapan.com/behind-the-scenes/how-i-got-credi...

I'm more amazed that Stripe hasn't reached out to you if you're getting 33% chargebacks. I thought the industry standard was that if your fraud rates are above 1% they'll flag your account, and above 2% you risk being permabanned by Visa/MC. (Perhaps that's outdated, I think I first heard that 10+ years ago.)