Memes

This flag is called "Thin Blue Line", which is a pro-police symbol. The origin is from the thought that supposedly the only thing keeping peaceful society insulated from total anarchy is a "thin blue line", or a small number of law enforcement officers who voluntarily put themselves between the two.

However, as noble as the origin sounds, the flag itself is only a modern artistic creation that can trace it's actual creation to the counter-protest of the "Black Lives Matter" movement in support of the police (the ones who were the subject of accusations of racial bias and discrimination against blacks in America) and it often interpreted as a racist dogwhistle, supporting acts of police brutality, extrajudicial killings, and authoritarianism in general.

It's a pretty right-wing affiliated symbol and you see it in conjunction with a lot of other conservative virtue signaling, iconography, and stereotypes.

The thin blue line is a symbol for the police. Used in the UK and US.

As a reaction to Black Lives Matter protests against racist police brutality, the (far-)right coined the term Blue Lives Matter to protest violence against the police.

Of course, the whole thing is disingenious. They support the police because the police in the US are often racist and they like that the police disproportionately beat up black people. When rioters stormed the US capital after Trump lost the election, plenty were waving blue lives flags, and didn't actually seem to care that much about endangering the police guarding the building.

TLDR hyper-partisan US political virtue signaling associated with the far-right.

Not american but that flag came about in support of the police after all the police kept killing innocent black people.

Bootlickers say they support the police with it. The same police that kill innocent people with no knock warrants and face little repercussion.

It's the blue life matters flag used by right wingers to show support to police who are fighting the black lifes matter movement.