Return to Revisions

If you want the div with full width then try adding "width": "100%" to the style attribute, like:

{
  "elmType": "div",
  "txtContent": "=if([$FlowStatus] == 'Expired', 'Expired', @currentField",
  "attributes": {},
  "style": {
    "width": "100%",
    "display": "table-cell",
    "text-align": "center",
    "vertical-align": "middle",
    "background-color": {
      "operator": "?",
      "operands": [
        {
          "operator": "==",
          "operands": [
            "@currentField",
            "Approved"
          ]
        },
        "#ABDB77",
        {
          "operator": "?",
          "operands": [
            {
              "operator": "==",
              "operands": [
                "[$FlowStatus]",
                "Expired"
              ]
            },
            "#FF6347",
            {
              "operator": "?",
              "operands": [
                {
                  "operator": "==",
                  "operands": [
                    "@currentField",
                    "Pending"
                  ]
                },
                "#FFD700",
                {
                  "operator": "?",
                  "operands": [
                    {
                      "operator": "==",
                      "operands": [
                        "@currentField",
                        "Rejected"
                      ]
                    },
                    "#bcbcbc",
                    ""
                  ]
                }
              ]
            }
          ]
        }
      ]
    }
  },
  "customRowAction": {},
  "children": []
}

Update:

Also, you can try adding padding to your div by removing display attribute as given below:

{
    "elmType": "div",
    "txtContent": "=if([$FlowStatus] == 'Expired', 'Expired', @currentField",
    "attributes": {},
    "style": {
      "padding": "0 25%",
      "text-align": "center",
      "vertical-align": "middle",
      "background-color": {
        "operator": "?",
        "operands": [
          {
            "operator": "==",
            "operands": [
              "@currentField",
              "Approved"
            ]
          },
          "#ABDB77",
          {
            "operator": "?",
            "operands": [
              {
                "operator": "==",
                "operands": [
                  "[$FlowStatus]",
                  "Expired"
                ]
              },
              "#FF6347",
              {
                "operator": "?",
                "operands": [
                  {
                    "operator": "==",
                    "operands": [
                      "@currentField",
                      "Pending"
                    ]
                  },
                  "#FFD700",
                  {
                    "operator": "?",
                    "operands": [
                      {
                        "operator": "==",
                        "operands": [
                          "@currentField",
                          "Rejected"
                        ]
                      },
                      "#bcbcbc",
                      ""
                    ]
                  }
                ]
              }
            ]
          }
        ]
      }
    },
    "customRowAction": {},
    "children": []
  }