firebase cloud functions error after previously working

Edit: Three days into this issue, countless efforts to fix, and it randomly starts working again. This is more concerning. I confirmed no code changes, I no longer get the SSL errors, and the cloud functions are returning successfully.

I am using Flutter and Cloud Functions. Everything has worked perfectly and just randomly stopped working. I get these errors on iOS and Android

SSL handshake aborted: ssl=0xaf688b98: Failure in SSL library, usually a protocol error
error:100000f7:SSL routines:OPENSSL_internal:WRONG_VERSION_NUMBER (third_party/openssl/boringssl/src/ssl/tls_record.cc:242 0xa86a9ce6:0x00000000)
Unhandled Exception: [firebase_functions/unavailable] UNAVAILABLE

If I change the HTTPS to HTTP, I don't get the error, but get a 302 error response instead.

cloud function:

    var MESSAGING_SCOPE = 'https://www.googleapis.com/auth/firebase.messaging';
var SCOPES = [MESSAGING_SCOPE];

exports.getAccessToken = functions.https.onCall((data, context) => {
    return new Promise(function(resolve, reject) {
        var key = require("./file.json");
        var jwtClient = new google.auth.JWT(
            key.client_email,
            null,
            key.private_key,
            SCOPES,
            null
        );
        jwtClient.authorize(function(err, tokens) {
             if (err) {
                 reject(err);
                 return;
             }
             resolve(tokens.access_token);
         });
      });
    });

Flutter call:

HttpsCallable callable = FirebaseFunctions.instance.httpsCallable('getAccessToken');
return callable();