As Tim already pointed out via the existing posts, B2 is designed for P11/12 and correct/typical filler metal for P22 should be B3.
However when welding dissimilar grades such as between P22 and and lower grade (P11/12 or even Carbon steel), B2 is used as a good "in-between" becuase the weld joint only have to be strong than the weaker side.
The minimum specifed tensile strength of ER 80S-B2 is still higher than that of the P22. You can even try to qualify a WPS using B2 between P22. From this point of view the joint will not have too high chance for an immediate failure and can even easily pass a hydro-test.
From a long term it depends on the service condition. Such as when creep strength, corrosion resistence, etc. are considered, the B2 weld metal will not be of matching chemical composition to provided desired properties.