We ended up with 3 spools of counterfeit WS2812Bs that had cheapskated out on some data line capacitors on the die. Totally fucked the emitted RF noise levels compared to the same thing build with genuine ones, and intermittently flaked out when trying to run high speed data updates long-ish distance - the lights 6-7m and 40-50 leds from the controller weren't reliable...
Manufacturer and their supplier were very good at fixing things for us once the problem was discovered and attributed to bad components, but it was a very stressful lead to the xmas supply chain back then. (Then the entire company fell apart for different reasons, but the stress and expense of that incident was quite likely a strong contributor to those the triggering of those company-ending reasons... :shrug:)