Thunderbird is software running on YOUR computer. If you want to use Thunderbird for an auto reply then you computer has to be on. Software does not run to well when the computer is turned off.

This is why the recommended method of doing auto reply is using the email providers server. Log into your account at your providers web mail page and see if they offer this option.

I see Thank you Airmail.

but will they ever change or do a upgrade/update on this ?

What kind of change do you think they can do. Thunderbird Is not your email provider. There are no Thunderbird servers. Like I said it is email client software running on your computer.

It helps to understand how email works if you learn the difference between client software and a provider.