Level conversion using transistors and pullup resistors tends to have vastly different properties for rising versus falling edges, which can distort or alter PWM signals, so you should probably avoid those types for converting PWM signals. Many companies marketing to makers sell cheap boards with these level converters, usually with descriptions that greatly over-promise the circuit's capabilities and usefulness. Truth is those transistor+resistors circuits have terrible performance for high speed signals and they badly corrupt signals like PWM and WS2812B (aka NeoPixel) data, where pulse widths matter.