You’re only seeing it from your white perspective. You don’t see the micro and macro racial aggressions people of color endure on a daily basis because you’re not of color. Many people see this reasonably small issue as one more racist act, not because of the one-off situation, but because of the constant BS they have to go through on a daily basis.
It’s honestly not “on us” because we put a racial twist on everything, it’s “on you” to try to understand a world where people who look like you and me have been racially attacking people of color for hundreds of years and it’s gotten worse over the last 5 years.
Don’t worry, it’s not your fault, nor are you to blame bc you’re white. It is, though, up to you to at least try to understand the reason a racial flag is raised in many surprising situations.