A new version (0003) of Replicant 6.0 has been released a few weeks ago.
It fixes an important issue that makes devices end up in a boot loop (the devices were crashing during boot, endlessly) when installing certain applications.
It also fixes a security issue that enables attackers to decrypt and/or
modify WiFi traffic.
This can be problematic if your security is relying on the WiFi encryption.
This can be the case if you are using WiFi to connect to your device to use
applications like Remote Keyboard over telnet. This can also be
problematic if you share your Internet connection through WiFi and some
services of the phone operator you use are available without authentication.
Because of the above, updating to this new version is strongly recommended.
See the update instructions on the wiki for that.
If your device is affected by the boot loop issue mentioned above, the update
instructions won't work, as they expect you to be able to easily reboot to
recovery.
In that case, to reboot to the recovery you have to first boot in safe
mode, and then to follow the update instructions to reboot to recovery.