Bitcoin Core has officially released version 31.0, introducing several significant updates and improvements. Key changes include an upgrade of the GUI framework to Qt 6.8 and an increase in the default database cache for systems with more than 4GB of memory from 450 MiB to 1024 MiB. The update also adds support for private broadcasting with the new -privatebroadcast option. Additionally, to prevent fee calculation errors, the static fee setting option -paytxfee has been removed, requiring users to rely on automatic fee estimation or specify transaction fees individually. The new version also enhances privacy and security filtering for wallet recovery and migration commands.