Simple hack that adjusts HUD to the correct aspect ratio and fixes stretching. You can see how it works here
Credits to BadSanta12345 who made the original fix for Alpha Project mod, but it doesn't work properly anymore.
Head over to Releases for a download link. Requires BF2 v1.5 patch & MS VC++ 2019 Redistributable (x86) installed on your system.
Copy the hudfix.asi, dinput8.dll and hud_config.txt to the main Battlefield 2 folder. NOTE: provided config only works with vanilla BF2 HUD, any HUD modifications will not work!