The Hebrew word "yada" refers to knowledge gained by experience, relationship, or intimacy, such as in Genesis 4:1, where Adam knew Eve, she conceived, and gave birth to Cain. In Exodus 33:13, Moses wanted God to be gracious to him by teaching him His way that he might know (yada) Him and Israel too, in 1 Kings 2:1-3, God taught how to walk in His way through His Torah, and in John 17:3, eternal life is knowing God and Jesus, so that is the goal of the Torah, which is also why Jesus said in Matthew 7:23 that he would tell those who are workers of lawlessness to depart from him because he never knew them. In Jeremiah 9:3 and 9:6, they did know God and refuse to know him because in 9:13, they had forsaken the Torah, while in 9:24, those who know God know that He delights in practicing steadfast love, justice, and righteousness in all of the earth, so delighting in experiencing those and other aspects of God's nature through our obedience to the Torah is the way to know God, and the Son, who is the exact expression of God's nature (Hebrews 1:3). God's nature is eternal, so His instructions for how to act in accordance with His nature are therefore also eternal, so the way know God does not change over time. In 1 John 2:4, those who say that they know Jesus, but don't obey His commandments are liars, and in 1 John 3:4-6, those who continue to sin in transgression of the Torah have neither seen nor known him.
Noah was temporarily instructed to eat the same foot as the other animals while on the Ark for obvious reasons (Genesis 6:21), so that was the lifting of that prohibition, not granting something new. In Genesis 7:2, Noah was given instructions for what to do with clean and unclean animals without being told how to tell the difference, and in 8:20, he knew the offer a clean animal, so he must have already been given instructions in that regard and knew not to eat unclean animals, and it wouldn't make sense to interpret the Bible as God flip flopping back and forth about whether or not something is an abomination against His eternal nature. The word used in Genesis 9:3 for what Noah was permitted to eat does not refer to predators of scavengers, which is what unclean animals tend to be. In 1 Peter 1:16, we are told to have a holy conduct for God is holy, which is a quote from Leviticus 11:44-45, where God instructed against eating unclean animals, and God's holiness is eternal, therefore so is the way to know Him through acting in accordance with His holiness.