UPDATE: I have tested Chromium (Chrome) versions 67, 87, 84, 80 and 79 to determine the lowest-possible version where the JS doesn't break. The results:
Chrome 84 (mid-2020) and 87 (late 2020) and newer = everything works perfectly, no errors in JS, no visual bugs
Chrome 80 (early 2020) = no errors in JS and normal site displays fine, but redesign layout is a bit derped as it uses some newer CSS features like `gap` in flexboxes
Chrome 79 and 67 = JS errors, site doesn't work or load properly