"This ends the prayers by David, the son of Jesse" (72:20). Why does a psalm titled "By Solomon" end that way, when later psalms are titled by David?

The line says what it says, and the book doesn't explain it. It closes a psalm whose title is "By Solomon" (72:1). And psalms titled by David still come after it. The first is Psalm 86: "A Prayer by David. Hear, LORD, and answer me, for I am poor and needy" (Psalm 86:1), and there are more, such as Psalm 101:1, 103:1 and 138:1. The book doesn't say how the line and these titles fit together, and these notes don't add an explanation. What can be said is what its words are. In Hebrew ends is kalah, which Brown-Driver-Briggs gives as "be complete, at an end, finished, accomplished, spent", and prayers is the plural of tefillah, the word in the titles "A Prayer by David" (Psalm 17:1, 86:1) (tap prayers).