Why is steam telling me to install a game I have installed?

This Reddit post by DuxteR7 says by replacing executables and a dll from a backed-up version of 1.5.97 they were able to play the downgraded version of Skyrim with some of the new Creation.ago What mods are you running? MrFelBlood I am very much confused, can anyone help me out by explaining what the issue is? 0 6 comments Add a Comment Denlim_Wolf Do not email about this! Runtime: 1.5.73 SKSE64: 2.0.12 Yet any time I run the SKSE Loader, I keep getting the error 'You are using a newer version of Skyrim than this version of SKSE64 supports'. In the meantime, please check for updates. If this version just came out, please be patient while we update our code. First window: You are using a newer version of Skyrim than this version of SKSE64 supports.Skyrim Script Extender (SKSE64) Date uploaded. Compatible with Skyrim Special Edition 1.6.640 from Steam.

hold of until Bethesda drops their next patch due to their script engine issues which plague the users now. You are using a newer version of skyrim skse64

Why is steam telling me to install a game I have installed?