Yes, there are new restrictions imposed by auDA on the registration of new id.au domain names. Prior to March 24, 2022, one could use any domain name name they fancy, such as the name of a hobby.
All id.au domain name registrations that are submitted after March 24, 2022 should refer to the domain registrant’s legal name. This can be a combination of any of the first names or surnames, acronyms or abbreviations. For example, someone with the name ‘John Smith’ could register for any of the following domain names:
johnsmith.id.au
jsmith.id.au
johns.id.au
js.id.au
If John Smith goes by the nickname ‘Johnny’, then he can register for the following domain names as well:
johnny.id.au
johnnysmith.id.au
johnnys.id.au