If this is not present in the system registry, the DLSS version and profile letter will not be displayed in MSFS. You need to manually add an entry to the system registry. Copy the code below
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\NVIDIA Corporation\Global\NGXCore]
"ShowDlssIndicator"=dword:00000400paste it into Notepad and save the file as DLSS_Indicator.reg (not as a text file, this is very important). Then run the file and agree to make changes to the system registry.
BTW, I’ve noticed even some YouTubers are repeating the mistake of calling the file from Cyberpunk “DLSS4” – the DLSS_Indicator clearly shows it’s still version 3 not 4.
Even in Cyberpunk it shows 3.