At job warning "warning: commands will be executed using /bin/sh" what to do?

[Bo Berglund]

When creating at jobs on my Ubuntu 20.04 LTS server on the command line I am
getting this warning:

"warning: commands will be executed using /bin/sh"

Why is this happening and will it affect the script that is scheduled to run?
The script has this shebang at the top:

#!/bin/bash

Will this override using sh or will the at job handler override the script
shebang?
How does it work?

The at jobs are created at night (04:45) for 24 hours of automated operation and
the bulk of what the jobs do are contained inside scripts called on the command
line.
The job creation is itself an at job contained in the job creation script...

I don't want to get into problems with different shell types for the
automation...


-- 
Bo Berglund
Developer in Sweden