Strapi Admin Page is just Blank

so I had strapi up and running and it worked fine.
I then wanted to install graphql and used yarn strapi install graphql it installed fine and I started strapi with yarn develop again, now when I try to open the admin panel i just get a blank black screen. The browser console logs a few errors:

EvalError: call to eval() blocked by CSP
Content-Security-Policy: Die Einstellungen der Seite haben das Laden einer Ressource auf eval blockiert ("script-src").
Source: ;(function r(e,t=!1){const o="6.0";let i…

English translation by me:

Content-Security-Policy: The pages settings blocked the loading of a ressource on eval("script-src").
Source: ;(function r(e,t=!1){const o="6.0";let i…

and my favorite:

TypeError: ye is undefined 

What can I do to fix this?

I just tried to uninstall the plugin again with yarn strapi uninstall graphql but the problem is still the same.

I “fixed” it by setting up a complet new instance of strapi and using that one now…