Cannot sign into my app using AzreADB2C. Getting browser error: ERR_HTTP2_PROTOCOL_ERROR

I am currently writing an app in ASP.Net Core 3.1. Everything has been working fine on localhost (IIS Express) for weeks, but all of a sudden, my authentication has stopped working.

I am using AzureADB2C for authentication. Whenever my app needs to redirect to the login page, I get the following error in Edge/Chrome.

Hmmm… can't reach this page
It looks like the webpage at https://localhost:44344/ might be having issues, or it may have moved permanently to a new web address.

ERR_HTTP2_PROTOCOL_ERROR

The browser also displays a warning telling me that the Connection to this site isn't secure

When I use the Azure Portal to test my user flow, I can see that Azure is redirecting me back to https://localhost:44344/AzureADB2C/Account/Error#id_token=eyJ0{snip}. The token actually seems to be valid, but I am not sure why Azure is redirecting to an error page.

Here are my Azure Ad B2C settings

  "AzureAdB2C": {
    "Instance": "https://MY_COMPANY_NAME.b2clogin.com",
    "ClientId": "MY_CLIENT_ID",
    "CallbackPath": "/signin-oidc",
    "Domain": "MY_COMPANY_NAME.onmicrosoft.com",
    "SignUpSignInPolicyId": "B2C_1_SignUpSignIn",
    "ResetPasswordPolicyId": "B2C_1_PasswordReset",
    "EditProfilePolicyId": ""
  },

Everything was working perfectly fine this morning. After restarting my PC, I launched Visual Studio, and my app would no longer work. I tested my app on another PC, and got the same errors.

UPDATE: After testing my user flow in the Azure Portal, with my local app not running, it looks like Azure is correctly redirecting back to https://localhost:44344/signin-oidc#id_token={token}. So the redirect to the error page is happening within the auth middleware. No errors are written to the output window, so I have no idea what is going wrong.

I tried rolling back my app to a previous commit from a week ago, but I am still seeing the same issue with older code that used to work.