I have been using RunProcess many times. This I have been doing, by first setting the PATH environment variable:

path = Environment["PATH"]
SetEnvironment["PATH" -> path <> ":/Applications/orca"]

since the external program is residing in /Applications/orca. I have then with success been running

RunProcess[{"orca", "input.inb"}]

Now, when I use version 13.3, I get the error message

RunProcess::pnfd: Program orca not found.  Check Environment["PATH"].    

If I call

Environment["PATH"]

I get

/usr/bin:/bin:/usr/sbin:/sbin:/Applications/orca

so this seems to be ok.
Any ideas? What is suddenly wrong?

Best regards
-Per Hedegård