Look at the pocket for the blue uniform , the flap is above the pocket , not side way like the Typ21 , blue also don't have arm pockets.
And we have no way to tell if the new blue uniform is made with the same fabric. It seems to me that the situation is just in mid transition and many sailors will still hang around with the old blue digital.
It is not unreasonable that in the same fleet , some ship will have the new ones , and some ship don't in the next few years.
Many other navies have this kind of working uniform for personals stationed on ship, since the need for a working uniform is bit different, it needs to be more flame resistant for example.
Also ,a side note PLA really don't have a different uniform for it's officers in combat/working uniform compared to the none-comms in any of it's branches, so that wouldn't make sense as reason to why the new blue uniform is introduced.
In my opinion , this new development is to be expected.
Oh yeah, I think you're right the navy blue does seem to be a different variant to the Type 21. It could be a working uniform instead of a combat uniform like the Type 21.
Though I think it still bears reiterating the PLAN, unlike other navies hasn't had separate 'working uniforms' with their Type 07 which has always been the
singular Ocean pattern across all spectrums within the PLAN. No woodland, nor any other variant.
Also, unlike the USN's NWU vs FRV, for instance, we don't know if this navy blue uniform is flame-resistant either. Like the NWU, the Type 21 certainly isn't.
While it makes sense for other navies to have separate uniforms for different tasks/stations, this hasn't been the case for the PLAN with their Type 07, which they have since transitioned to the navy blue, which was introduced first, and now onto the Type 21 Woodland
concurrently from the looks of it. So I'm not sure what you mean by "mid-transition" with some sailors still retaining their old Type 07 when none of them in the video wears it anymore.
We also have photos of ship-bound officers wearing the Type 21 Woodland, in conjunction with others wearing the navy blue in the same setting. So this rationale of separate uniforms for on ship and on land purposes again seems pretty thin IMO.
So I think the point still stands in terms of just under what circumstance would an officer wear the navy blue or the Type 21 Woodland, and thus far there still has been no solid indication as to the reasoning behind the different uniform choice beyond mere speculation at this point when, once again, there didn't used to be such a choice at all with the Type 07.