I actualy think I just came across why this is and how to fix it https://github.com/golang/go/issues/24057 this issue gives some information on the distinction between TAR and ZIP but to summarise it seems that ZIP support for symlinks is weak and TAR handles them by default I recommend you just switch over to storing the app in TAR and seeing if it helps
this might also help but you likely already read it https://itch.io/docs/itch/integrating/compatibility-policy.html
Best of luck :)