There is already a patch for skipempty. However it uses function "json_object_array_del_idx" from libfastjson. This function is present on upstream but it is not yet in rhel-8.4.0 libfastjson package.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (rsyslog and its related dependencies bug fix and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2021:4193