Weird scroll up behavior on Dropdown

When trying to scroll down the results of a quick search on PC, the window keep scrolling back up to the highlighted result. Using Firefox and Windows 10 Steps to reproduce : - go to https://app.cardnexus.com/profile/inventory - click "Add cards to inventory" - click the search input box and type "arcane" or anything that will result in a long list - move the cursor to the second result, remain until the + button turns to solid yellow - scroll down The results window then scrolls back up to the highlighted result This behavior seems to go away after scrolling with cursor hovering over the scrollbar. I can record my screen to show the bug happening in case I wasn't clear enough by text.