This isn't a Blu-ray but rather 4K that requires its own player (but can still play Blu-rays). Most 4Ks are region free however this will be completely in Japanese. Also by its design, this will be the
only Lupin TV series outside of any possible future productions that will have a 4K release (not sure on Part 3 due to not sure whether 16mm or 35mm, Part 2's out of the question,
apparently Parts 4 and 5 are 720p so those are upscaled anyway and don't know about Part 6, Lupin Zero apparently is even a low resolution upscale since it was using a similar method to Megalobox where they downsampled, put a filter and upscaled for a "retro" look). As mentioned in the past, there's not really too many options for Lupin in 4K.
A trailer has been posted showing examples from Episode 1:
There are some minor changes such as color revision, some spots that got removed and a more stable picture that was advertised but the most noticeable one sadly is that apparently an AI filter is used scrubbing out the detail such as trees when Jigen gets changed into his driver's outfit. The only plus about it is that it doesn't have the "frozen grain" that was on the earlier Japanese Blu-rays that kind of did get distracting yet knowing detail got wiped out...
The reception this is getting is
rather negative (even Yasushi Yamaguchi as in the creator of Tails from the Sonic series is complaining, that surprised me since I didn't know he's a fan of the series too like Naoto Ohshima) meaning that Discotek is unlikely to release the 4K in the US with the English dub, the same reason why The Mystery of Mamo doesn't have an English 4K release. Can see an Italian release though but not for a while and even then it would only be first Italian dub + Japanese with Italian subs if it happens.
I think quite a lot will stick to the Discotek Blu-ray if they already have it, a shame really as some people were looking forward to this...