Not sure if the "VPN in Firefox" can be used for individual tabs however you can exclude websites from using the VPN. There is also a monthly Data limit bar that will tell you how much you use for the month and will reset on the first of each month and the Firefox browser should notify you when you are approaching this 50GB limit with a prompt in the browser.

https://support.mozilla.org/en-US/kb/built-in-vpn https://support.mozilla.org/en-US/kb/built-in-vpn#w_manage-website-settings

If you need more than 50GB each month then there is the separate subscription based "Mozilla VPN" app.

thank you for the Courtesy of the detailed Response

Can we use FIrefox VPN in other browsers like chrome? does Firefox Vpn provides static IP.

Can we use FIrefox VPN in other browsers like chrome? does Firefox Vpn provides static IP?

The built-in VPN in the desktop Firefox web browser is only for in Firefox.

https://support.mozilla.org/en-US/kb/built-in-vpn

VPN is a built-in Firefox feature that adds privacy by routing your browser traffic through a secure proxy server and masking your IP address. .. Unlike Mozilla VPN, which protects your entire device, the built-in VPN only masks traffic that originates in Firefox.

If you want to use VPN with another web browser and that browser does not have its own built-in VPN, then you need a standalone VPN app as Mozilla has the subscription based Mozilla VPN. https://www.mozilla.org/products/vpn/