PixiJS Assets Problem Loading Spritesheet

[mareydo]

Hello guys!
I'm trying to implement new @pixi/assets to load spritesheet from my Sanic backend.

When I load local json+png from frontend it works normally, but when I do request on backend, I will get:

ERROR Error: Uncaught (in promise): Error: [Loader.load] Failed to load BACKEND_URL.json.
TypeError: Cannot read properties of null (reading 'baseTexture')
Error: [Loader.load] Failed to load BACKEND_URL.json.
TypeError: Cannot read properties of null (reading 'baseTexture')

[Assets] BACKEND_URL.png could not be loaded as we don't know how to parse it, ensure the correct parser has being added

When I look into the network monitor, the frontend version is invoking calls to some loadImageBitmap callback and then the png file,
while the backend version doesn't request anything further whatsoever.

I'm using the same json, png, PIXI v6.5.2

Thanks for any tips

[mareydo]

Update:
I've made it work from backend when I had changed the BACKEND_URL
from http://localhost:7070/api/texturePack?criteria=spritesheet&parameter=2&format=data.json
to http://localhost:7070/data.json