Array Merge Recursive old vs new values

I would like to merge two arrays to compare old vs new values. For example, $arr1 is old values $arr2 is new values.

In case when the data is deleted $arr2 is an empty array. Example:

$arr1 =  [
  "databases" => [
    0 => [
      "id" => 1
      "name" => "DB1"
      "slug" => "db1"
      "url" => "https://www.db1.org"
    ]
  ]
];

$arr2 = [];

For this my expected output after merge is

$merged = [
    "databases" => [
        0 => [
            "id" => [
                'old' => 1,
                'new' => null
            ],
            "name" => [
                'old' => "DB1",
                'new' => null
            ],
            "slug" => [
                'old' => "db1",
                'new' => null
            ],
            "url" => [
                'old' => "https://www.db1.org",
                'new' => null
            ],
        ]
    ]
];

if arr2 is different then the values should be present in the new field instead of null.

For example:

$arr1 =  [
  "databases" => [
    0 => [
      "id" => 1
      "name" => "DB1"
      "slug" => "db1"
      "url" => "https://www.db1.org"
    ]
  ]
];

$arr2 =  [
  "databases" => [
    0 => [
      "id" => 5
      "name" => "DB2"
      "slug" => "db2"
      "url" => "https://www.db2.com"
    ]
  ]
];

expected output:

$merged = [
    "databases" => [
        0 => [
            "id" => [
                'old' => 1,
                'new' => 5
            ],
            "name" => [
                'old' => "DB1",
                'new' => "DB2"
            ],
            "slug" => [
                'old' => "db1",
                'new' => "db2"
            ],
            "url" => [
                'old' => "https://www.db1.org",
                'new' => "https://www.db2.com"
            ],
        ]
    ]
];

Case 3 is when $arr1 is empty but $arr2 is populated:

$arr1 = [];

$arr2 =  [
  "databases" => [
    0 => [
      "id" => 1
      "name" => "DB1"
      "slug" => "db1"
      "url" => "https://www.db1.org"
    ]
  ]
];

and the expected output is:

$merged = [
    "databases" => [
        0 => [
            "id" => [
                'old' => null,
                'new' => 1
            ],
            "name" => [
                'old' => null,
                'new' => "DB1"
            ],
            "slug" => [
                'old' => null,
                'new' => "db1"
            ],
            "url" => [
                'old' => null,
                'new' => "https://www.db1.org"
            ],
        ]
    ]
];

The inbuilt php functions cannot format the data in old vs new format so was wondering how to go about this? Any solutions/suggestions would be appreciated.

Update

Here is what I had tried before:

1. I had tried simple array_merge_recursive but it does not store the source array. So if you have $arr1 key not there, the final merged array will only have one value.
2. I tried some more recursive functions late in the night but failed so in essence didn't have anything to show for what I had tried. However, this morning, I came up with the solution and have posted it as an answer in case anyone needs to use it.

source https://stackoverflow.com/questions/68870342/array-merge-recursive-old-vs-new-values