Adding custom hover text using json to a SharePoint list column


You can try this and customize to suit your need

{
  "elmType": "div",
  "style": {
    "font-size": "12px"
  },
  "txtContent": "@currentField",
  "customCardProps": {
    "formatter": {
      "elmType": "div",
      "txtContent": "[$Description]",
      "style": {
        "font-size": "12px",
        "color": "green",
        "padding": "5px"
      }
    },
    "openOnEvent": "hover",
    "directionalHint": "bottomCenter",
    "isBeakVisible": true,
    "beakStyle": {
      "backgroundColor": "white"
    }
  }
}

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