Features that according to your GP was disabled by default. And according to others in this discussion thread, disabled by default in the upstream also.
If you read the GitHub discussion these features are usually compiled in but not actually exercised until the user enabled then in the UI. The debian packager has changed the compile-time configuration to disable them at compile-time, making them unavailable to the user in the UI. Regardless of the makefile defaults this be a breaking change.
There is a some confusion because the flags that control these features at compile-time do default to OFF if not provided, but the installation instructions in the same documentation also tell you to compile with XC_ALL set to ON. The maintainers themselves talk about all features being enabled at compile-time in the discussion thread and even consider removing these compile-time flags altogether to prevent compiling keepassxc without these features. So "disabled by default" is not really an accurate understanding. It is clear that the intended configuration from the authors is for all features to be compiled in and available.
