Same mindset applies to trading sites. The CS2 transition created a real split between platforms, with some updating quickly and others still working through compatibility issues affecting which skins they accept. Checking when a site was last updated matters just as much as it does with bonus pages.
Learn more about which trading platforms have genuinely made the switch to CS2 skins, since the gap between the ones that adapted and those that did not is larger than it looks. Item eligibility and trade hold terms are worth reading carefully before moving any inventory to a new platform