more general solution

app/assets/javascripts/discourse/app/lib/body-scroll-lock.js

@@ -41,7 +41,7 @@ const isIosDevice =
   (/iP(ad|hone|od)/.test(window.navigator.platform) ||
     (window.navigator.platform === "MacIntel" &&
       window.navigator.maxTouchPoints > 1));
-let locks = [];
+export let locks = [];
 let locksIndex = /* @__PURE__ */ new Map();
 let documentListenerAdded = false;
 let initialClientY = -1;

app/assets/javascripts/select-kit/addon/components/select-kit/select-kit-collection.js

@@ -5,6 +5,7 @@ import { modifier } from "ember-modifier";
 import {
   disableBodyScroll,
   enableBodyScroll,
+  locks,
 } from "discourse/lib/body-scroll-lock";
 
 @tagName("")
@@ -16,10 +17,18 @@ export default class SelectKitCollection extends Component {
       return;
     }
 
+    const isChildOfLock = locks.some((lock) =>
+      lock.targetElement.contains(element)
+    );
+
+    if (isChildOfLock) {
       disableBodyScroll(element);
+    }
 
     return () => {
+      if (isChildOfLock) {
         enableBodyScroll(element);
+      }
     };
   });
 }