withTransaction does not roll back changes when error is thrown if await is not used inside of Promise.All

Working with Data
, ,
1 
      await tran_session.withTransaction(async () => {
          const id_arr = Object.keys(req.get_tar.blocked).map((key) => {
            return ObjectId(key);
          });
          await Promise.all([
            await user.updateOne( // does not roll back changes if "await" keyword is removed
              { email: req.user.email },
              { $pull: { tar: { name: { $eq: req.params.name } } } },
              { session: tran_session }
            ),
            await user.update(  // does not roll back changes if "await" keyword is removed
              { _id: { $in: id_arr } },
              {
                $unset: {
                  [`blocked_by.${req.user._id}_${req.get_tar.name}`]:
                    undefined,
                },
              },
              { session: tran_session, multi: true }
            ),
          ]);
      }, tran_option);

If I call the update functions with the await and if there is an error thrown, the changes will not be rolled back.

Why is this?