Are patterned mousepads okay for modern mice?

Probably yes, unless you’re using a very cheap or old mouse. Modern optical sensors track surface texture, not color, so patterns like floral prints or galaxy swirls don’t confuse them. The exception is super-low-end mice with older sensors, which can get glitchy on high-contrast patterns. If your mouse acts weird on a busy pad, the mouse is the problem, not the mousepad.