What is sh in the accessibility permissions in Catalina?
You don’t need it so remove all things there you don’t positively trust and know you need. Then, wait for a dialog to pop up asking again for permissions so you can scrutinize what and why you’re giving up control of your Mac.
In this case, the sh process can run all sorts of scripts so it’s like putting a wedge in the door, anyone that uses the wedge can now get in. You’ll only know they used the wedge and not which script or program invoked the wedge.

Accessibility
Shows apps that run scripts and system commands to control your Mac. Deselect the app if you want to prevent it from controlling your Mac.

https://support.apple.com/en-in/guide/mac-help/mh32356/10.14/mac/10.14.5
&gt;&gt;&gt; which sh
/bin/sh


>>> man sh
...
 bash - GNU Bourne-Again SHell
...
Bash  is  an  sh-compatible  command language interpreter that executes
       commands read from the standard input or from a file.  Bash also incor-
       porates useful features from the Korn and C shells (ksh and csh).

       Bash  is  intended  to  be a conformant implementation of the Shell and
       Utilities portion  of  the  IEEE  POSIX  specification  (IEEE  Standard
       1003.1).  Bash can be configured to be POSIX-conformant by default.