The only solution I have seen so far, is to serialize the JSON into a string and save it as a longtext. E.g. GitHub - paulgaumer/Strapi_ColorPicker_Plugin
This requires to manually set columnType to longtext: Strapi_ColorPicker_Plugin/Category.settings.json at 7f1580dfa00098c930d7590cf6b3bad3f74bffc8 路 paulgaumer/Strapi_ColorPicker_Plugin 路 GitHub
In case you find a better solution, please let me know 