YSK: If you updated to the latest version of iOS 15 and don’t like the search bar living at the bottom of the UI in Safari you can tap the “aA” symbol and move it back up to the top.
from /r/YouShouldKnow
YSK：如果你更新到最新版本的iOS 15，不喜歡Safari瀏覽器中生活在用戶界面底部的搜索欄，你可以點擊 "aA "符號，將其移回頂部。