Short answer: tinted windows are banned in most of Mexico, and rolling down the windows (at least the front windows) should keep you out of trouble in >99% of cases.
First, the law (mirror) seems to say that tinted windows are forbidden in most (all?) Mexico:
[In all] Mexico, tinted windows are prohibited. They are banned. Except some tinted windows made by manufacturers.
This article says the Mexican federal highway police will now be confiscating cars with tinted windows so dark that they cannot see inside, until the owners remove the polarizing paper. This is in accordance with Article 13 of the federal tranportation rules. It does not say what will happen with cars with factory tinting, since that cannot be removed.
Second, on the enforcement of this law, it is sometimes enforced:
TIJUANA – Hundreds of drivers have been stopped in Tijuana and ordered to remove after-market tint from the windows of their vehicles this week after a new law intended to help reduce crime went into effect.
More sources. The enforcement seems very random.
I did witness it myself that it is still currently enforced, at least in Tijuana.
Regarding the effectiveness of rolling down one's windows to avoid triggering the police, http://www.city-data.com/forum/san-diego/321508-warning-message-those-who-driving-their.html says:
I talked with the Police at the Ocho Street station last week. When driving in Tijuana, rolling down your front windows is OK for a tourist. Do it as you approach the border and while in Tijuana. It is only a ban in Tijuana, Rosarito and south is OK.
I went to the 8th street Police station (Tijuana) to find out what was up. I was told that the ban applies to only the front side windows. Rear side and back are OK (as in California). NO tint (other than factory) is permitted, even my light tint. They told me that, as a tourist, when in Tijuana just keep the front windows down, no problem. It's what I do, and -- no problem.
When I get lit up, I immediately roll down all four windows in the car and when I pull over, I turn on the interior lights for them if it's at night.
In the very unlikely event one gets pulled over despite having rolled down one's windows, one can use this trick:
And while I have not had to do this, several of my Amigos have had great luck with not speaking Spanish to the cop (whether or not they know Spanish) and then saying they don't understand the cop's accent or why they were pulled over - being polite the entire time - and say they are going to call 078 to get help translating (078 is the Baja California tourist help line - it is staffed by English speaking operators). Invariably, the cops all the sudden get a more important call and have to leave immediately and let you off with a verbal warning. https://www.bajanorte.com/en/assistance-078/
Note that, from the same source:
if you have Cali plates, you are at a higher likelihood for being pulled over, regardless of tint or actions.