0👍
Okay got it fixed now.
I had too add to the fastapi python-file:
from fastapi.middleware.cors import CORSMiddleware
app.add_middleware(
CORSMiddleware,
allow_origins=["*"],
allow_credentials=True,
allow_methods=["*"],
allow_headers=["*"],
)
And yes, I know that using a wildcard is not good practice.
Source:stackexchange.com