Why is there so much confusion?

I would check to see what flasher you have. Some LED lights will not have sufficient resistance to make the flasher work.
I would and did change my flasher to an electronic version that does not require much load to make it work. Then order the LED lights that you want.

As already mentioned, the "hyperflash" is caused when the draw of the LED lights are so low it causes your vehicle to think the bulb is out. However, this is a case of may or may not since you're only changing the rears. The fronts and sides may (emphasis on may) still pull enough to avoid the problem. But, if planning to replace them all with LEDs, might as well also change the flasher to an electronic version now so you don't have to deal with it as you change out the bulbs to LEDs.

Careful about the front light changing to LED. If the chassis has lamp outage, you may need to install resistors to keep the system from saying you have lamp out.
This would happen with clearance (parking) lamps as well as turn signals.
I had to go back to conventional in front as the ballast resistors used power and got very not warm but hot!

I installed the Bargman LEDs on my '03 E-450 and had to change the flasher for them to work right.

I didn't have any problem when I installed them on my 2007 E-450.

I am a Neanderthal. I trust nothing. Until I changed (toad) to 100% LED's I would give the vehicle a Monday morning walk-around with flasher and tail lights energized. Then a routine springtime bulb turnaround including third brake light. Rationale? Someone bashing into me because a front or rear burnout caused a no flash. Every time the OEM flasher seemed to indicate a burned out bulb it was during the first 10% of a long commute.

CORRECT LED lamps plus a rather pricey Sure Power burnout proof flasher solved that problem. But I still perform my Monday morning walk-arounds.

Quicksilver has 24-volt lighting so it uses much more reliable (1157-style 24-volt bulbs) Since I no longer drive after sundown the headlight issue is moot. The bus utilizes a motorized flasher. It has four tail/stop lights but the rear alternating flashing lights were welded and finished over.

If you need resistors, research their value meaning specifications then buy metal aluminum heatsinked resistors on eBay. One tenth the cost and ten thousand percent better quality than what is sold in kits.

BUT

BCM Body control modules on brand new vehicles makes choosing aftermarket lamps more critical. Research before you buy or modify.

They do sell special LED compatible flasher relays.

Just make sure to get a true electronic flasher and not one that just has a resistor built in, which defeats the whole purpose of switching the tail lights to LED.

Why is there so much confusion? Because the manufacturers are deliberately creating products that cannot be serviced by the average Joe Citizen any more. For every home grow Joe Citizen home grown garage mechanic is one less opportunity for the manufacture to make a buck on service calls. It's a conspiracy you know, to get your money. They market the product to sound like it's something you absolutely MUST have, get you hooked, and then bleed your pocket book.

The reason you can not get a "Straight answer" is because it an not be predicted

BUT if it does. they make a fix (Resistor) Kind of defeats the power saving feature but LED's have other features.

DID not on my Workhorse.. but your rig may be different and it is impossible to say till you try it. Also a HD flasher may cure hyper-flash.

If you have hyperflash from LED tail turn signal bulbs, you have different choices depending on what vehicle you have.

If you have a flasher relay you can upgrade to an LED compatible one or HD version.
If like on my 13 Tahoe, it is controlled by the BCM (body control module) then you have to either get inline resistors for the turn signal bulb socket wiring or get the BCM custom reprogrammed.