Hi @Monalv-MSFT , @Yitzhak Khabinsky
Looks like I found the issue/solution-
I have been deploying my .ispac using .bat file (reason for my problem)
ISDeploymentWizard /S /SP:"%~dp0\xxx.ispac" /DestinationServer:"xxx" /DestinationPath:"/SSISDB/xxx/xxx"
pause
To resolved this, I have altered my environment Variable in the below order (on my window 10 machine). No more Script task issues using targetserverversion2019 on runtime now using with .bat file deployment.