Bitcoin Core 31.1 includes a fix for an IP-address leak affecting the privatebroadcast feature. The release notes say that, in some circumstances, connections used the ordinary internet instead of the enabled privacy network.
A separate fix addresses a chainstate database issue that caused repeated rewrites of large portions of the database during normal operation. The notes also list changes to validation, networking and several other components.
These are statements about the specific defects described by the maintainers, rather than a general assurance about anonymity. The official release page provides the full change list, supported operating systems and installation references. Operators should use those instructions when assessing their own setup.