Steam is a reasonably common app and tends to accumulate junk in the appdata/local/steam/htmlcache folder
It is only a cache for the store and advert display so should be safe to clean
[Steam Browser Cache*]Section=GamesDetect=HKCU\Software\Valve\SteamDefault=FalseWarning=This will also delete the thumbnails and custom background images of the games in your Library.FileKey1=%LocalAppData%\Steam\htmlcache|*.*|RECURSEFileKey2=%LocalAppData%\VirtualStore\Program Files*\Steam\appcache\httpcache|*.*|RECURSEFileKey3=%LocalAppData%\VirtualStore\Program Files*\Steam\config\cookies|*.*|RECURSEFileKey4=%LocalAppData%\VirtualStore\Program Files*\Steam\config\htmlcache|*.*|RECURSEFileKey5=%LocalAppData%\VirtualStore\Program Files*\Steam\config\overlaycookies|*.*|RECURSEFileKey6=%LocalAppData%\VirtualStore\Program Files*\Steam\config\overlayhtmlcache|*.*|RECURSEFileKey7=%ProgramFiles%\Steam\appcache\httpcache|*.*|RECURSEFileKey8=%ProgramFiles%\Steam\config\cookies|*.*|RECURSEFileKey9=%ProgramFiles%\Steam\config\htmlcache|*.*|RECURSEFileKey10=%ProgramFiles%\Steam\config\overlaycookies|*.*|RECURSEFileKey11=%ProgramFiles%\Steam\config\overlayhtmlcache|*.*|RECURSEFileKey12=%ProgramFiles%\Steam\userdata\*\ugcmsgcache|*.*|RECURSE
G'day DeadGuppy and Welcome,
it's already covered in winapp2.ini or you could cover it by an INCLUDE yourself.