Firebase provider sign-in is not working inside facebook/messenger/instagram in-app browser webview. Error 403: disallowed

my team uses firebase auth and we recently run into major problems. We started advertising our website on facebook. Unfortunately, facebook app opens all the links in the in-app webview. Google blocked support for signing in with provider through embedded browser, so none of the users that opens our webapp through facebook/messenger/instagram apps can sign in. Google/Facebook sign-in returns 403: disallowed_usegagent and it is impossible to sign up. Is there any workaround? Has anyone experienced a similar issue?

How do I log into firebase authentication?

To sign a user into your app, you first get authentication credentials from the user. These credentials can be the user's email address and password, or an OAuth token from a federated identity provider. Then, you pass these credentials to the Firebase Authentication SDK.

Not sure about Google, but for Facebook I would recommend: