@ced117, this is not mistake, it is a positive consequence of a nice strategy change at Jolla:
As denoted in the IRC community meeting logs, they ceased to avoid GPLv3 software in general.
Instead they started distributing GPLv3 software as optional RPMs for SailfishOS, i.e. what formerly was (until SailfishOS 2.2.1) in the mer-tools repository. Now (since SailfishOS 4) only the RPMs for the basic SailfishOS (i.e., which may be installed by default) are still kept free of GPLv3 software.
This change in strategy allowed Jolla to update the historic, last GPLv2 version of bash (v3.2.57) to a recent bash v5, but only as an optional RPM. At the same time a recent busybox version of ash is installed by default, along with a symlink which calls ash in its (limited) bash compatibility mode.
RPMs at Openreps can simply conflict to busybox-symlink-bash in their spec file and bash will be automatically installed, if it was not installed before. But preferably their shell scripts shall be freed of BASHisms.
Users can simply uninstall the busybox-symlink-bash RPM and bash will be installed, if it was not installed before. Users not capable of accomplishing that do definitely not need a bash for interactive use.
While this may break some apps for now, it is easy to adapt them.
Much more importantly, Jolla’s license strategy change is a small, but relevant step forward for Jolla and SailfishOS.