Baal HaTurim: “So your generation will know that I housed the Bnai Yisrael בסכות” There are tagin on the letter "כ" to allude to the law that until 20 amos a person realizes he is sitting in the shade of the sukkah.
The letter "כ" is usually written in the Torah without tagin. Sefer Tagin lists 55 places in the Torah where the letter "כ" has attached 3 tagin and 74 places where the final letter "ך" has four tagin. Baal haTurim only comments in one other place on the letter "ך" with tagin (Bereshis 12,3 מברכיך).
The first Mishnah in Sukkos states the law that the סכך is invalid if placed higher than 20 amos. The Gemara lists this verse as basis for one of the three opinions as to the reason why it is invalid, since the verse emphasizes that one should know they are sitting in a Sukkah and one does not realize it if sitting in the Sukkah with the סכך beyond the normal range of vision (above 20 amos).
