@thuquyen
Inside of a network you can already map any domains to resolve to internal hosts. So this is mostly a simbolic decision, I don't see any effects of this decision other than letting everyone now that .internal will be kept from public use.
ICANN approves use of .internal domain for your network https://www.theregister.com/2024/08/08/dot_internal_ratified/
https://www.theregister.com/2024/08/08/dot_internal_ratified/