Can someone explain exactly how overcontributions to your 401k works?

I just realized I’ve contributed more than allowed to my 401k and it’s looking like I’ll get double taxed (how?) plus a fee for early withdrawal since I’m under the age. Is there still a way to avoid these taxes or is it too late since it’s almost a new year.

I’d assumed that the 401k contributions would stop getting withdrawn once I hit the $23k limit but obviously that’s not the case.