Seem to recall that blinking/flashing taillights/brake lights are a no no.

Turn signals and 4 way flashers are the only legally allowed flashing lights other than emergency vehicles and other exemptions re: tow trucks, mail carriers, slow moving vehicles, etc.

Flashing brake lights violate both state law in terms of flashing lights, and also FMVSS for modifying the intended design of the lamp.

If they are illegal, why did you have me buy them for my truck when we changed out to all LED??

It’s called dynamic brake lights. Teslas have them, OEM. If it’s a rapid deceleration the brake lights will flash rapidly.

Hazard flashers are required and can be activated in addition to the brake lights "for the purpose of warning other operators of other vehicles of the presence of a vehicular traffic hazard requiring the exercise of unusual care in approaching, overtaking, or passing."

I'm not familiar with the KIA flashing brake lights but on some BMWs the brake light comes on continuously when the pedal is pressed, under heavy braking applications flashing hazard lights blink as well

In the video below the blinking center high mount brake light would be illegal but not the blinking hazard light down low

Hazard flashers are 4 way flashers...
...
The main difference under state law between turn signals and 4 way flashers is that turn signals have to flash between 60 and 120Hz, whereas, IIRC, there is no restriction on 4 way flashers so you can wire in strobe patterns, as I have on previous vehicles..

hazard flashers CANNOT flash the CHMSL under federal law. CHMSL is restricted to a single function only, and that's to be a CHMSL.

They're not called 4 way flashers in state law, because they aren't required to flash 4 ways. The front have to flash simultaneously and the rear have to flash simultaneously but there's no requirement that front and rear flash together. I couldn't find any requirement for flash rate of either those or turn signals in the RCW



State law too. That's why I pointed out that the flashing CHMSL in that video would be illegal

WAC 204-21-060
Turn signal lamps.
(1) Turn signal lamps visible to approaching or following drivers must:
(a) Flash at a rate of sixty to one hundred twenty flashes per minute.
(b) Flash in unison. Except that a turn signal consisting of two or more units mounted horizontally may flash in sequence from inboard to outboard. The lamps may either be extinguished simultaneously or lighted simultaneously.
(c) Be mounted and operated as follows:
(i) On motor vehicles, turn signal systems must:
(A) Have four separate lamps consisting of at least two single-faced or double-faced turn signal lamps on or near the front and at least two single-faced lamps on the rear. Except that a truck-tractor or a truck chassis without a body or load may be equipped with one double-faced turn signal lamp on each side in lieu of the four separate lamps otherwise required on motor vehicles. If double-faced turn lamps are used, they must be mounted ahead of the center of the steering wheel or the center of the outside rearview mirror, whichever is rearmost.
(B) Be spaced as far apart as practical.
(C) Have the optical center of the front turn signal at least four inches from the inside diameter of the retaining ring of the lower beam headlamp unit, fog lamp unit, or passing lamp unit. Except original equipment turn signals that emit two and one-half times the minimum candela requirements may be closer.
(ii) For motorcycles, the front and rear turn signal lamps must be at least nine inches apart, except that front turn signals on motorcycles manufactured after January 1, 1973, must be at least sixteen inches apart.
(iii) On the rearmost towed vehicle in combination of vehicles, turn signal systems must be equipped with at least two single-faced turn signal lamps on the rear. The signal system on a combination of vehicles towed by a motor vehicle equipped with double-faced front turn signal lamps may be connected so only the double-faced turn signal lamps on the towing vehicle and the signal lamps on the rear of the rearmost vehicle are operative.
(2) Side turn signal lamps must:
(a) Meet SAE Standard J914.
(b) Be mounted on the side not lower than twenty inches or higher than seventy-two inches.
(c) Flash with the front and rear turn signal lamps on their respective sides of the vehicle. On vehicles with sequential turn signal lamps, the side turn signal lamps must flash with the front turn signal lamps.
(d) Flash with the rear turn signal lamps, if the side lamps flash when the hazard warning switch is actuated.

This list doesn't tell you anything about good or bad dealerships, it just lists a few dealerships that charge a markup on a single vehicle to a single person.

How's that saying go?

1 is random, 2 is a coincidence, 3 is a pattern?

Where's the pattern? It's a bunch of random dealerships, not a list of every dealership's practices.