I have excel from office 2021 and it is not long path aware nor long path enabled. So, it cannot "see" long path named files. You'll see this same issue in Windows 10 too. Make a super deep path and try saving a file there via Excel's "save as" dialog box. It won't let you due to the long paths not being supported in excel. Easiest way to make a deep folder is from the command line. Have ChatGPT write you a script to do that.
Microsoft have enabled support for long path names. But, each application has to "opt in" for long path name support. I wrote my own application and it works like a champ with long path names. But, I'm still very disappointed that even though the path name can be 32K bytes, it has a basic limitation that each element is limited to 256 bytes. That means each folder name is limited to 256 bytes and each filename can only have 256 bytes. So, to get a 32K full path filename, it has to be over 100 folders deep - which is crazy deep.
Seems to me that Microsoft does the minimum long path name support - it's almost as if they just want that check box on the feature list. Same deal with the registry entry for enabling case sensitive filenames - I tried that once: it breaks everything.
To sum up: Long path names only work for applications that have been ported to the correct APIs. Most applications have not been ported.