Interesting, the costuming here looks much more Raiders-esque. Maybe it's just the wetness, but the overall darkness of everything looks more like the first film. Indy's costume got lighter and lighter as the films went on.
However, there are a couple things that suggest that it is in fact a different costume for the flashbacks and not just wetness making it look different. First, the jacket has the baggier fit and lighter look of the lambskin leather from Raiders. You can see that the shoulder seams extend past the end of Ford's actual shoulders like here:
The thinness of the lambskin is what gives Indy's jacket its wrinkled and creased look.
In the presumably "present day" scenes where Ford is not wearing any CGI markers, the jacket is lighter in colour, heavier in construction, and more traditionally fitted like the TLC and KOTCS versions:
TLC was a heavier lambskin and I think they moved to cowhide for KOTCS if I recall correctly. Technically, a heavier, more durable leather jacket makes more practical sense for Indy, but I think the lighter, wrinkled Raiders version looks more unique and distinctive. The later versions look more like generic 40s bomber jackets.
On one hand, I'm glad they are trying to recapture the Raiders look for the flashbacks, but I'm saddened it also seems to indicate that they are sticking with the vastly inferior KOTCS look for the rest.