Steps to reproduce:

1. Install Zabbix Agent2 and keep service's account as "Local System"
2. Allow remote execution at Agent2 configuration file: AllowKey=system.run[*]
3. Set logging debug level to 4
4. Add as templtated or direct item key (unsigned): system.run[netstat -a -n|find /c "CLOSE"]
5. Wait for result or push it manually
6. See "▒▒▒ ▒▒▒▒㯠: \" in Agent's log (in Russian: "Нет доступа: \", in English: "Access denied: \"

Note: if i remove part, starting from "|" symbol from item key system.run[netstat -a -n|find /c "CLOSE"] (as system.run[netstat -a -n]), i get result (but without filtering via console command "find"). Any try to add "|" symbol to command make an error in output.

Possible affected to system.run[] with powershell and "|" used in expressions too (not tested).

Result:
See screenshot run_1 with combined server console and agent2 log file

Expected:
Unsigned number (from 0 to any other)