Wooden ceiling on the 1st floor with vapor barrier or vapor retarder

Hello forum members,

I am renovating my hallway on the first floor and then my attic.

When renewing the ceiling, I noticed that there is a draft. Therefore, I sealed the rafters with a vapor barrier. About 4 sqm of ceiling area.
I know that a vapor barrier is not necessary when both sides are heated rooms.

Could I still install a vapor barrier on both sides?
For the sake of airtightness?

I do not know the roof insulation, as it will only be renewed in a few years. House built in 1992.

Best regards, Edison

If the attic under an insulated roof is sealed to the extent that the air cannot circulate there, that is anything but advantageous.