These are two ComfyUI nodes used for converting input prompts into the Danbooru tag format (tag_a, tag_b, ...) and outputting the converted prompts.
https://github.com/GHOSTLXH/ComfyUI_Danbooru_Formatter
git clone https://github.com/GHOSTLXH/ComfyUI_Danbooru_Formatter
comfy node install ComfyUI_Danbooru_Formatter