When Da Vinci painted the Mona Lisa, he did paint her eyebrows, but over time, they wore away due to cleaning and maintenance to the point where it’s no longer visible today.
Also, a high forehead was considered beautiful in the Renaissance so women used to pluck their eyebrows and hairline to make their foreheads appear higher. Eyelashes were also unfashionable and were often trimmed/plucked. Here's an extreme example of this: