Is the GSTR-1 filing last date of 13 Jan 2021 also for quarterly filer?

The last date for GSTR-1 of 13 January 2021 as notified also applicable for those who file GSTR-1 on a quarterly basis? The reason I am asking is because normally the last date for quarterly filers is the 31st (or the last day) of the month. Is there any particular reason for early deadline this time? And does that mean that GSTR-3B for December too has to be filed before that?