Now there arose a new king over Egypt, who did not know Joseph. Exodus 1:8
I seriously doubt someone in Egypt did not know Joseph. The Egyptians kept great records of advancements, victories, and about their leaders. Joseph became the #2 person in the kingdom during his life and that would make it into the official records.
Imagine a president not knowing Washington, Lincoln, or FDR.
More likely the new Pharaoh chose to ignore the progressive changes of Joseph and his treatment of the Israelites.
The new king saw them as a threat to the internal security of the nation.
He did not realize the blessing of the Israelites at bringing food and commerce to the nation. The new king chose to ignore the blessings of the past for the sin of the future.
In my opinion, the people of Israel should have long left Egypt and gone back to the land of Canaan. That is the land they should inherit, not Egypt.
But the people got complacent and prospered easily in the lush Nile River delta, where good water and pastureland increased their flocks.
In the U.S., we elect a new leader every four years, though a person may serve as president for eight.
Many times a new president wipes out the agenda and precepts of the outgoing president, making vast changes.
For instance a pro-life president may ban partial-birth abortion and a new president makes it legal within the first hundred days of taking office. The next election sees a turnover and that new president makes it illegal again.
A modern rewrite of the featured scripture might say, “Now there arose a new president over the United States, who did not know Jesus Christ!”
And when this happens that president begins to enslave the nation in sin, much like that Pharaoh of old enslaved the people of Israel.
If you keep reading in Exodus, you find the new king pushed an agenda of genocide – the abortion of the living. The killing of the unborn or any particular group is the downfall of a nation, as Egypt discovered many years later under the Israeli deliverance of Moses.