Deceased person's tax return when to file

My mother passed away in February, 2021.  She is due a refund on her 2020 tax return.  So, I have to mail in her return.  Cannot file it electronically.  

 

My question is, is there any reason that I should NOT go ahead and submit her return for 2020 now so the IRS can start processing her refund??  Her refund that is due is a pretty substantial amount and I don't want the IRS to keep the money any longer than necessary.

 

Thank you.