Non-violent protests do work, though they require you hit a critical mass to become effective. There even exists a 3.5% rule[1] in political science whereby authoritarian governments will topple if 3.5% of the population engages in nonviolent protest.

One of the more famous examples here in the US is that of the equal rights marches in the 1960s ultimately leading to the end of segregation.

What I'm not sure of, though, is what kind of impact there is on the required percentage of people participating when we have media outlets like Fox News, which was demonstrated to have fabricated images during events like the Black Lives Matter protests to make them look as if they were violent.

1. https://en.wikipedia.org/wiki/3.5%25_rule

While I agree with your basic premise, that 3.5% "rule" is much more of an observed effect than an actual rule.

There needs to be an actual mechanism for the protests to bring about the fall of the authoritarian regime. Unfortunately, in our current context, a lot of the feedback mechanisms that should cause protests to change actual policy and affect the people in power are broken, largely due to the Republicans' efforts over the last several decades to eliminate accountability both from the actual institutions and as a valid concept in our national consciousness.