i suppose it is a KYC/AML thing which they set based on USD value of your withdrawal not a fixed amount of bitcoin. that is why it has changed without notice.
checking my account it says i am limited to 1337 (haha leet) amount of daily bitcoin withdrawal. and it was 2000 bitcoin before.
Mine says this as well however I still have a basic account it says. I have had this account open for over 3 years - is your account nearly this old as well? I am confused by the limit. I move a decently large amount out over the past several days and I had no trouble at all - depositing a BTC was rather slow but it showed up without any additional problems.. I wonder if the feds are cracking down again.. glad I am moving to more cold storage.