I’d first test whether Firefox is blocking something the sites need. Click the shield icon in the address bar on one of the affected sites and turn off Enhanced Tracking Protection for that site, then reload and try again. Checkout pages often rely on third-party payment/fraud-check scripts that can break if blocked. Also try Help → Troubleshoot Mode. If the sites work there, the cause is probably an extension, theme, or hardware acceleration. I’d especially check ad blockers, privacy extensions, coupon extensions, and script blockers. For the NYTimes scrolling issue, since it only happens inside articles, it may be a site script or layout issue being affected by an extension or tracking protection rather than a trackpad problem. If Troubleshoot Mode fixes it, re-enable extensions one by one to find the culprit.