Is wearing a flag patch on a backpack against regulations?

It is not a violation of the 1st Amendment Free Speech clause as such regulations must yield to the Constitution. See Smith v Goguen 415 US 566 (1974)

Backpack? I wasn't aware the Army had any. I guess that's where you stow your gun and BFR. Give me 50 and get rid of that backpack!

PFC, you should read the reg, not look towards social media.

I would say you're barking up the wrong tree. I will have to admit that the military service has a regulation for everything, and having been retired for 30 years now I am in serious need of an update, I would say worry more about the guy who owns the patent on your backpack than a regulation covering the wear of the American Flag on it. Don't take this as an answer but rather my opinion.

No

Why would it be an issue, my grandkids have American flag patches on their backpacks, if any one has a problem they can take it up with me

chuckles at the answers that don't address the point of the question... can a patch... U.S. Flag or otherwise... be sewn onto a U.S. Military Issue Field Pack/Rucksack... or any piece of military issued equipment????
idk about today's regs... but when I served... making changes to issued equipment was a problem during...
Inspector General Inspections...
because ... U.S. Military Issue gear is supposed to be maintained... AS ISSUED??
Combat Equipment is NOT part of your Dress Uniform.
It has waterproofing that can be compromised by adding holes.
Adding starch and ironing degrades the camouflage aspect.
Adding anything to a combat uniform/equipment, that is not subdued... is a TARGET.
IF the Military wanted a U.S. Flag (subdued) on your backpack... IT WOULD BE ISSUED THAT WAY!
Your Combat Uniform and Gear are created to give you maximum survivability ...
Millennials ... NO you cannot play Army YOUR WAY...
COMBAT ... IS NOT A $#@$%$# GAME >(
IT'S LIFE OR DEATH.
Accept what you get ... AS IT IS... DECADES OF TRAIL/ERROR/EXPERIMENTATION HAS BEEN PUT INTO THAT EQUIPMENT....
--> IT IS MADE TO KEEP YOU ALIVE...
RESPECT THAT....
DON'T $#@% WITH THAT!!!!

as I read your Question, I am thinking, I am Retired, and I don't Care,
it a Flag Patch, it not the United states Flag.
it someone showing respect to America in there own way, what is the Problem? some individuals get way to carried away sometimes when reading rules and Regulations.
and like to abuse power, it just a piece of cloth made to look like the united states flag, it does not make it, the united states Flag.
Example , a Girls Bikini that made to look like the united states Flag, does not make it the UNITED STATES FLAG, YOU ARE NOT GOING TO DEMAND SHE STRIP OUT OF HER BIKINI BECAUSE IT BREAKS Regulations.
so lets not worry about things that are not worth worrying about! now if you are Talking about a United States Solder Taking A Knee During Morning or Evening Colors, then we have something to talk about, or a military Member That Disrespect the Fallen Solders coming Home, Under a American Flag, then lets talk.
has that ever happen?

I found the Whole UCMJ, and the Regs to be cumbersome, and overly restrictive... it takes the MY out of the meaning of Army. Example.
My ass should have been treated better, But My CSM saw thing differently..... How short sighted.