AddressSanitizer (or ASan) is a programming tool that detects memory
corruption bugs such as buffer overflows or use after free. AddressSanitizer
is based on compiler instrumentation.
The llvm.org states that Sanitizers have found thousands of bugs everywhere.
Sanitizers running during CI can prevent bugs from taking up residence. They
are helper tools to maintain bugs out.
The development flatpak is meant to be used exactly
that: development. It isn't and won't ever be released
as a regular Flatpak application.
GNOME Setting is still supposed to run as a host system
tool.