Superfish Submenu Indicator Arrow Won't Display When js/css Aggregation Turned On

I have exactly the same problem. Only on the taxonomy terms pages. With js aggregation enabled.
A message appears in the console:
Uncaught ReferenceError: assignment to undeclared variable p
The solution described in #7 does not help.

#6 doesn't really work. As soon as you flush the cache again the down arrows disappear again. Why doesn't some fix this? I'm using Drupal 10 and the same problem occurs.