It looks like Civitai is only supplying jpg files and the generation info is in the json for the page.
Civitai Helper: Failed to find generation info on remote image at https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/31e4e728-b97c-475d-a7ca-d6b2065e972d/width=450/3416735.jpeg.
Civitai Helper: /stable-diffusion-webui/models/Stable-diffusion/matrixHentaiPlus_v30.civitai.info missing generation info for https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/e6452635-4342-4dc0-9121-dbe6263b8767/width=450/3416736.jpeg. Processing https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/e6452635-4342-4dc0-9121-dbe6263b8767/width=450/3416736.jpeg.
Civitai Helper: Failed to find generation info on remote image at https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/e6452635-4342-4dc0-9121-dbe6263b8767/width=450/3416736.jpeg.
Civitai Helper: /stable-diffusion-webui/models/Stable-diffusion/matrixHentaiPlus_v30.civitai.info missing generation info for https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/97bbb67b-0b0a-4854-89f0-b58b24887b4c/width=450/3437820.jpeg. Processing https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/97bbb67b-0b0a-4854-89f0-b58b24887b4c/width=450/3437820.jpeg.
Civitai Helper: Failed to find generation info on remote image at https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/97bbb67b-0b0a-4854-89f0-b58b24887b4c/width=450/3437820.jpeg.
Civitai Helper: /stable-diffusion-webui/models/Stable-diffusion/unrealvision_v10.civitai.info missing generation info for https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/a8eddc98-2aed-4739-90a3-b660b33229c5/width=450/4711436.jpeg. Processing https://image.civitai.com/xG1nkqKTMzGDvpLrqFT7WA/a8eddc98-2aed-4739-90a3-b660b33229c5/width=450/4711436.jpeg.```
It looks like Civitai is only supplying jpg files and the generation info is in the json for the page.