finally i think it works now

unfollow_all.js

@@ -25,8 +25,18 @@ async function unfollowUser(user) {
         e = await fetch(`https://scratch.mit.edu/site-api/users/followers/${the}/remove/?usernames=${user}`, {
             "method": "PUT",
             "body": "{}",
+            "credentials": "include",
             "headers": {
-                "x-csrftoken": getCookie('scratchcsrftoken')
+                "User-Agent": "Mozilla/5.0 (X11; Linux x86_64; rv:128.0) Gecko/20100101 Firefox/128.0",
+                "Accept": "application/json, text/javascript, */*; q=0.01",
+                "Accept-Language": "en-US,en;q=0.5",
+                "Content-Type": "application/json",
+                "x-csrftoken": getCookie('scratchcsrftoken'),
+                "X-Requested-With": "XMLHttpRequest",
+                "Sec-Fetch-Dest": "empty",
+                "Sec-Fetch-Mode": "cors",
+                "Sec-Fetch-Site": "same-origin",
+                "Priority": "u=0"
             }
         });
         e = await e.text();