Be very aware of when ANY conversation happen s between you and a tl and etl. If they start to talk about ways to improve, its safe to assume that the conversation is being documented aka PDD (performance discussion document) 3 of these conversations need to happen to proceed to a formal write up. You should be pulled aside by your team lead in a private off stage area and you are supposed to sign the documentation. You are put on a probationary period depending on what the coaching was for. Operational and safety could be a year and attendance could be 90 days to 6 months. It all depends. Key point is yes you should be fully aware and have signed something.
If you have a violation during your probation then you go to a D Day or a final then shit gets real really fast.
I would personally go to etl HR and ask to see the documents. If you haven't signed it can't legally stand. He or she keys everything and should keep all documents for upwards to 3 years.