[ParaLLEl-GS] forces de-interlacing, options and interlacing hint broken

I believe I've found a bug with Parallel-GS on some specific games. I first noticed when trying Gran Turismo 4 1080i mode that the interlacing was being forced disabled by the renderer. Then I noticed the same happening in Dead or Alive 2. If you turn off all de-interlacing settings and hints, using the vulkan or software renderer, you get a result like this:

This is how I would expect interlaced frames to look. However, with identical settings, in Parallel-GS, some sort of de-interlacing is being forced, and I can't find any way to disable it:

As you can see, the two fields are being blended, leaving some stray interlaced artifacts scattered around the image. This also means that the "no interlacing hint" works in Vulkan and Software, but not Parallel-GS. I tested parallel-gs in the standalone PCSX2 build and the same thing happens as in retroarch.

Even though the de-interlacing looks pretty good, and barely noticable in motion, it's not accurate, so I assume this is not what is intended. It also breaks the interlacing hint, meaning you can't have progressive mode nor pure interlaced image, only this de-interlaced hybrid. I've only noticed this issue with these 2 games so far. Let me know if I am missing something here.

Reproduce the issue in Parallel-GS with Gran Turismo 4 1080i or Dead or Alive 2, comparing Vulkan or software rendering against the Parallel-GS renderer with de-interlacing settings and hints disabled. Trace the renderer's interlacing and de-interlacing handling, then verify that the no-interlacing hint can produce the expected pure interlaced image without forced blending.