from white paper

Warm wallet:
Warm wallets are stored on a totally separate server that has all the security measures to be
protected:  all  communication  ports  except  for  the  blockchain  synchronization  ones  are
blocked, no user has access to the server directly, the wallet's password is encrypted, etc.

Cold wallet:
Cold wallets are stored on air-gapped PCs in the COSS office in Singapore. These computers
have  no  internet  connection,  and  the  transactions  from  the  cold  wallets  are  processed
manually by our financial managers.
The majority of funds is stored in the cold wallets.

can COSS explain please? its not decentralize.