I am using Acrobat Pro from my school's subscription. I need the freehand highlight function as most of my documents are scanned books. As I remember, Acrobat Pro DC 2017 and 2020 had this function. However, the newest Acrobat seems to remove the function (at least I didn't find it). I searched discussions and checked several but most of them were talking about older versions. I am wondering if the newest Acrobat has the freehand highlight function or if I should wait for half an hour until the scanning is finished.
How my interface looks like and the version of my Acrobat.
You have got the modern viewer of Acrobat (New UI).
Add annotations to your PDF like comment, text box, highlight, underline, strikethrough, or draw freeform by using the commenting tools on the menu.
To know more about New experience, please refer to this article https://helpx.adobe.com/acrobat/using/new-acrobat-experience.html
You can disable the new UI