On 6th May 2022 Linden Lab announced new last names for Mother’s Day (US) which are now available. These limited new last names will remain available until Friday 13th May 2022. You can change your account name here. and find the FAQ here.
Here is the full list of current last names now available….
The lab will announce more new last names throughout the year and for anyone that wants to suggest a new last name for Second Life then here is the Last Name Suggestions form.