It seems that there is some renew attack from some malware on this kind of files and
I highly suspect that some "repair tools" from less known companies are the problem. It is probably related to the shortcut that you use to launch the game (which will eventually modify some game related dll, writing
them with an incorrect version, as corroborated by the new date-time-stamp for their "Date Modified" attribute for these dll). I haven't found the exact way they use to accomplish this exploit, but for now, I copy the game folder in another folder and when
the problem occur, I just replace the original file, unmodified from the backup folder to the working folder launching the game, and I am done... for few days.
NOTE: it is not always the same dll which they replace. In my case, with the game
ESO, they (the malware) have targeted granny2_x64.dll as well as
icuuc55_x64.dll and icuin55_x64.dll
They may have targeted different dll after I marked the attacked ones with a Read Only attribute.