Does this happen even if the user is already logged in? I have email, Google, and FB authentication, and if the user first signs up with email, and logs in with email, then subsequent auths with Google or FB get associated with that user’s account by Bubble.

What happens is that if the user is logged out, and then if you try to use Google/FB or another auth, Bubble thinks two accounts are being created with the same email.

So just log in first using email/Bubble, and when logged in, trigger the auth workflow.