I feel you bro @Bulauski2005
It is almost impossible to find nowadays, also oficial website does not sell anymore. I bought it on this site:
Bescherm je OnePlus 9 Pro met deze Karbon Bumper Case zwart. Bekijk en bestel direct! ✓ Gratis verzending NL ✓ Voor 17.00 besteld vandaag verstuurd ✓ Veilige betaling.
You can pay via paypal, so no worries. It did cost like 37€ shipping included, not cheap but worth every euro.
I don't know where are you from, but they shipped to EU really fast, like 3 days. Took me like months to find it, so thanks a lot to the users sugesting "AsK GoOgLe"