Roth 401k overcontribution question

I switched jobs midyear and accidentally contributed over 19,500 to my 401ks.

• Job A I contributed 9,750 regular 401k
• Job B I contributed 9,750 regular 401k and an extra 4,000 in a Roth 401k.

How do I correct this? I figure I have to contact my 401k plan administrator and ask for them to return my 4,000 from my Roth 401k. I understand I'll get a 1099-R on that where I'll report any gains on my 2022 tax return.

How do I handle my 2021 tax return? It'll show the over contribution. How do I indicate that I'm correcting it?