It’s not just that. Look up the subsequent verses of the Star Spangled Banner.

It’s about rounding up “fugitive” runaway slaves. It’s why no one discusses the latter verses.

This is factually incorrect. The Star-Spangled Banner is about the War of 1812. The first stanza actually ends on a question, which is answered in the second stanza. I actually really like the first two stanzas together. The poetry in the second is beautiful.

O say can you see, by the dawn's early light,
What so proudly we hail'd at the twilight's last gleaming,
Whose broad stripes and bright stars through the perilous fight
O'er the ramparts we watch'd were so gallantly streaming?
And the rocket's red glare, the bomb bursting in air,
Gave proof through the night that our flag was still there,
O say does that star-spangled banner yet wave
O'er the land of the free and the home of the brave?

On the shore dimly seen through the mists of the deep
Where the foe's haughty host in dread silence reposes,
What is that which the breeze, o'er the towering steep,
As it fitfully blows, half conceals, half discloses?
Now it catches the gleam of the morning's first beam,
In full glory reflected now shines in the stream,
'Tis the star-spangled banner - O long may it wave
O'er the land of the free and the home of the brave!

The only stanza that mentions slaves is the third. It says:

And where is that band who so vauntingly swore,
That the havoc of war and the battle's confusion
A home and a Country should leave us no more?
Their blood has wash'd out their foul footstep's pollution.
No refuge could save the hireling and slave
From the terror of flight or the gloom of the grave,
And the star-spangled banner in triumph doth wave
O'er the land of the free and the home of the brave.

Here the “band who so vauntingly swore” is referring to the British. The “Hireling” refers to Hessian mercenaries hired by the British, and “slave” refers to American slaves who (justifiably) defected to fight for the British, having been offered their freedom in exchange. When the British fled they abandoned those slaves and mercenaries to “the terror of flight and the gloom of the grave.” Problematic certainly, but not about rounding up runaway slaves.

Finally we get the fourth stanza:

O thus be it ever when freemen shall stand
Between their lov'd home and the war's desolation!
Blest with vict'ry and peace may the heav'n rescued land
Praise the power that hath made and preserv'd us a nation!
Then conquer we must, when our cause it is just,
And this be our motto - "In God is our trust,"
And the star-spangled banner in triumph shall wave
O'er the land of the free and the home of the brave.

The person who wrote the anthem, Francis Scott Key, was indeed a slave owner, but was a complicated individual. He spoke out against slavery, and actually gave free legal representation to some slaves seeking freedom. That said, he also represented some owners of runaway slaves. Like I said, complicated individual (as are many people who live in times with ethics we rightly find abhorrent).