But I can't tell: Is the 2021 release actually a "cut" of the 2017 film, or a remake?
I understand a "cut" to be a "post-production" compilation from the same film – e.g., the same raw recordings may be compiled into a "theatrical cut," "unrated cut," "director's cut," etc. A "remastered cut" might use the same film but redo or enhance computer-generated content.
In contrast, I would assume that a version that uses substantial new film would not be called a "cut," but instead would be properly termed a "remake."
How much of the 2021 release was filmed prior to the 2017 release?