It’s become a symbol of defiance against big government. There’s nothing inherently offensive in that, unless it is displayed by an auditor for the Internal Revenue Service, such as my neighbor!

Also, it has been embraced by many on the political right who oppose liberalism and what that means to them. It seems to represent a mindset of “leave me alone and let me do whatever I want”, which they call freedom. It suggests that they don’t want to follow rules imposed by others, ie the government. The fact that someone feels the need to fly that flag and proclaim that political belief in a residential neighborhood seems somewhat extreme to me, and that has been substantiated by conversations I have had with some of them.

You can Google it and learn lots more.