As a product nears release, the rate of change slows down, and along the way, the ship room goes through stages known as Tell Mode and Ask Mode.
In Tell Mode, any changes to the product do not require prior approval, but you are required to present your changes to the next ship room meeting and be prepared to explain and defend them. The purpose of this exercise is to get teams accustomed to the idea of having to present their changes to the ship room as a warm-up for Ask Mode. There is also the psychological aspect: If you have to present and defend your changes, you are going to be more careful about deciding which changes to make, how you will go about making them, and how thoroughly you're going to validate those changes. For example, if a bug could be fixed by applying a targeted fix or by rewriting the entire class, you are probably not going to choose to rewrite. (In theory, the ship room may reject your changes after the fact, and then you have to go back them out. But this is rare in practice. The ship room usually lets you off with a warning unless your transgression was particularly severe.)
The next stage of scrutiny is known as Ask Mode. In this stage, any proposed changes to the product must be presented to the ship room before they can be submitted. Rejection is more frequent here. Time has passed and the bug bar has gone up, and because it is easier to get forgiveness than permission.
Note that there can be multiple levels of ship room. There may be a local feature team ship room, then a group-wide ship room, then a product-wide ship room, and it is not uncommon for each ship room to be in a different mode. For example, the local feature team ship room may be in Ask Mode, the group-wide ship room is in Tell Mode, and the product-wide ship room isn't looking at individual bugs yet. This means that when you want to make a change, you need to get permission from your local feature team, and then after you commit the change, you need to get forgiveness from the group ship room.