I think humans have a default toward tribal thinking. We view "us" as superior and more cherished than "them". I don't think most people will agree that they, personally, are prone to it; but it shows up in a hundred different way in life. I spotted that thinking in myself when I saw that the next oracle wasn't a terrible foreign enemy, but our Jerusalem. This should remind us that when we act like the enemies of God, we shouldn't be surprised to find ourselves on a list that includes those we're acting like.
It seems like this chapter is related to the events immediately before, during, and/or after the reign of Hezekiah.
After another pass at II King 16 & 17 and II Chronicles 27 & 28, Israel has fallen and has been hauled away. God has orchestrated a priest to come back and teach His ways, but the people just add that to their previous worship. Meanwhile Judah is still alive, but not thriving under Ahaz. Both book passages end with the death of Ahaz and the introduction of his successor, his son Hezekiah.
Now the Blue Letter Bible chronological reading list sends us back to Isaiah. Previously in Isaiah, he was prophesying about the end of Israel and two beautiful chapters about the Messiah.
Isaiah has been prophesying about the end of Israel as a cautionary tale for Judah. We've seen that Assyria will be the instrument to crush Israel and then come for Jerusalem, sending Judah's villagers fleeing in fear. But the Lord will deal with Assyria and raise up a remnant of his people.
Amos has had some bad news for Israel (and Judah) (and some of us). They had forgotten how to do right. And even those waiting for the Day of the Lord were also carrying around idols. He does provide a very narrow path out for a remnant. The messages conclude in Chapter 6 and then the visions begin.
Following the Blue Letter Bible, I am pausing after Isaiah 8 (as well as after II Kings 16 and II Chronicles 28) and reading all 9 chapters in Amos. The shift is from Judah back to Israel and the rule of Jeroboam II.