Hi,
We have checked for this issue from our side on various PHP versions but we have not encountered this issue on any of them. So this issue can be a server specific issue.
So I recommend you to raise a ticket at https://webkul.uvdesk.com/en/customer/create-ticket/
And on the ticket please share your FTP details and the QloApps admin details with us.
We will hunt down the issue and resolve it.