I was reading on the Disney Tourist Blog the other day that his theory is that Splash isn’t closed at DL yet as they are waiting until they are further along with the refurb at WDW first to use some of the “lessons learned” before they start on the DL version. He didn’t think they’d wait until they were entirely done with Splash at WDW before closing at DL but that it would still be a bit its closed. Perhaps they will wait until the fall of 2023 to close it…
I think it's more than that. I think the literal team of Imagineers working on Splash in WDW will be the same one working on Splash in DL. I don't think they have 2 separate teams to handle these refurbishments, so we won't see DL started until WDW is almost finished.