In Yonah 4 verse 5 says:
וַיֵּצֵ֤א יוֹנָה֙ מִן־הָעִ֔יר וַיֵּ֖שֶׁב מִקֶּ֣דֶם לָעִ֑יר וַיַּעַשׂ֩ ל֨וֹ שָׁ֜ם סֻכָּ֗ה וַיֵּ֤שֶׁב תַּחְתֶּ֙יהָ֙ בַּצֵּ֔ל עַ֚ד אֲשֶׁ֣ר יִרְאֶ֔ה מַה־יִּהְיֶ֖ה בָּעִֽיר׃
Now Jonah had left the city and found a place east of the city. He made a booth there and sat under it in the shade, until he should see what happened to the city.
So Yonah had shade in his Sukkah. Verse 6 says:
וַיְמַ֣ן יְהוָֽה־אֱ֠לֹהִים קִיקָי֞וֹן וַיַּ֣עַל ׀ מֵעַ֣ל לְיוֹנָ֗ה לִֽהְי֥וֹת צֵל֙ עַל־רֹאשׁ֔וֹ לְהַצִּ֥יל ל֖וֹ מֵרָֽעָת֑וֹ וַיִּשְׂמַ֥ח יוֹנָ֛ה עַל־הַקִּֽיקָי֖וֹן שִׂמְחָ֥ה גְדוֹלָֽה׃
The LORD God provided a kikayon , which grew up over Jonah, to provide shade for his head and save him from discomfort. Jonah was very happy about the plant.
There seems to be a clear question, “If he had a sukkah with shade, why did he need a kikayon?” and a simple answer - “The kikayon gave valuable extra shade.”
Is there any commentator who asks the question? I am not satisfied with the simple answer.