Nothing, this is not about that.

This change gives you the guarantee that .internal domains will never be registered officially, so you can use them without the risk of your stuff breaking should ICANN ever decide to make whatever TLD you’re using an official TLD.

That scenario has happened in the past, for example for users of FR!TZBox routers which use fritz.box. .box became available for purchase and someone bought fritz.box, which broke browser UIs. This could’ve even been used maliciously, but thankfully it wasn’t.