OpenAI only returns part of the ID token?

Plugin Development
1

My plugin has the following settings in “ai-plugin.json” .

  "auth": {
    "type": "oauth",
    "client_url": "https://accounts.google.com/o/oauth2/v2/auth",
    "scope": "email",

I can login by My Google account, and my plugin had received the Authorization header like:

"authorization": "Bearer ya29.{RANDOM_CHARACTERS}"

I tried to get the uid with the following code but get “FirebaseAuthError: Decoding Firebase ID token failed. Make sure you passed the entire string JWT which represents an ID token.”

import * as admin from "firebase-admin";
import * as functions from "firebase-functions";
...
      async function(req: Request, res: Response) {
        try {
          let token = "";
          if (req.headers.authorization) {
            token = req.headers.authorization.split(" ")[1];
            const decodedToken = await admin.auth().verifyIdToken(token);
            functions.logger.info(decodedToken.uid);
          }
        } catch (err) {
          functions.logger.error(err);
        }

{RANDOM_CHARACTERS} has 207 chars, is this just part of the ID token?
Or is there a mistake in my code?