Memory estimation/ wan models is broken since release 0.34, impossible to generate long (more than 65 frames) clean videos with loras

### Custom Node Testing

- [x] I have tried disabling custom nodes and the issue persists (see [how to disable custom nodes](https://docs.comfy.org/troubleshooting/custom-node-issues#step-1%3A-test-with-all-custom-nodes-disabled) if you need help)

### Expected Behavior

you should be able to generate at least 81 frames for wan T2V (i2v). when using CausVis or any other lora
at 480,720p (with built-in nodes)

### Actual Behavior

It always gives black or distorted results even if there are plenty of free memory for more than 65 frames

### Steps to Reproduce

Load a Wan2.1T2V or Vace (14B) 720p around 10-14GB per file, use CausVIs14blora (any version), connect any other lora.
KSampler Steps 4, default or dpmpp_2m scheduler, or ddim...
use > 65 length, 81, 105, or 121 frames, etc.
you can use 592x832 or 1280x820 resolutions or similar...

### Debug Logs

```powershell
no need
```

### Other

I've fixed it locally by rolling back several changes taken from 0.34 release .. so locally it works as intended , I can generate 121+++ length videos w/o issues even at 720p. but in 0.39+ it's not working, only less than 65 steps