This is the upcoming Olympus M.Zuiko Digital ED 150-400mm f/4.5 TC1.25X IS PRO Lens, which is now alreadly listed at B&H.
According to the Nokishita, this new lens has now been officially registered in Russia. This means it will be officially announced very soon.
In August 2020, Olympus M.Zuiko Digital ED 100-400mm F5.0-6.3 IS lens (Amazon/ B&H/ Adorama) was officially announced.