Hello!
From what I see on your forum, it seems there is an issue with the Patreon plugin:
Specifically here:
I believe $.cookie usage has been deprecated and dropped from Discourse, and since Ember 5 is enabled, it errors directly. 
I don’t have an immediate solution for you; the plugin needs to fix this.
EDIT: Made a PR:
https://github.com/discourse/discourse-patreon/pull/131