PowerShell, on Windows of necessity, performs re-quoting of your arguments behind the scenes.
This invisible re-quoting doesn't always work as expected, such as in this case.
You can solve the problem by tweaking your quoting:
... PUBLICPROPERTY=`"`" # `-escape the " chars.
... 'PUBLICPROPERTY=""' # use enclosing '...', so " chars. can be used as-is
Note that using '...' won't work if you want to include the values of PowerShell variables / expressions in the argument.
Additionally, in PSv3+ you can use --%, the stop-parsing symbol, to make PowerShell pass the remaining arguments through as-is, as if you had called from cmd.exe / a batch file (including expansion of environment-variable references such as %OS%).
... --% PUBLICPROPERTY=""
Again, you won't be able to reference PowerShell variables or expressions in the arguments that way.
As for what happens without the techniques above:
PUBLICPROPERTY="someValue" becomes
PUBLICPROPERTY=someValue
PUBLICPROPERTY="some Value", due to whitespace, becomes
"PUBLICPROPERTY=some Value", i.e., the entire argument is enclosed in "...".
PowerShell-internally an argument such as PUBLICPROPERTY="someValue" has its quotes stripped: if you pass such an argument to a PowerShell cmdlet or function, it will see just PUBLICPROPERTY=someValue.
On passing such a value on to an external program, PowerShell decides situationally whether double-quoting is needed, but that quoting is then only ever applied to the entire argument - the initial placement of the " chars. is lost.
Thus, PUBLICPROPERTY="someValue" turns into PUBLICPROPERTY=someValue and is passed on as-is, because it contains no embedded whitespace, so PowerShell applies no double-quoting.
By contrast, PUBLICPROPERTY="some Value" turns into PUBLICPROPERTY=some Value, which is passed on as "PUBLICPROPERTY=some Value", because the presence of whitespace requires double-quoting in order to preserve the value as a single argument.
Note that PowerShell only ever applies double-quoting to arguments passed to external programs, because that is the only style of quoting that can be assumed to be understood by all programs.
The re-quoting logic has changed over time and has bugs, which, regrettably, are here to stay due to backward compatibility concerns.
E.g, '3 " of rain' becomes "3 " of rain", which is broken, because the embedded " lacks escaping; the workaround is to anticipate that and explicitly do what PowerShell should be doing automatically: escape the embedded " as " for the benefit of the external program: '3 " of rain'
