Generating a grid of coordinates inside a polygon, each 1km apart

Question

Given a polygon in JSON, I want to obtain a square grid of coordinates inside a polygon, each 1km apart.

Here is a function that I've written, it's generating coordinates but in some situations I get a grid of coordinates with a spacing of 1.2 km or 0.8km, but I want that distance to be 1km.

def generate_coords_inside_polygon(self, polygon):
    try:
        bbox = self.helpers.get_polygon_bbox(polygon)
        print(bbox)

        min_lat, min_lon, max_lat, max_lon = bbox
        earth_radius = 6371  # Earth's radius in kilometers

        coordinates = []

        generated_coords = set()
        # Start from the minimum latitude and longitude
        current_lat = float(min_lat)
        current_lon = float(min_lon)

        while current_lat <= float(max_lat):
            while float(current_lon) <= float(max_lon):
                coordinates.append((current_lon, current_lat))
                # Move 1 kilometer to the right (longitude)
                # change radius, default 0.2
                desired_radius = 1
                current_lon += (desired_radius / (earth_radius *
                                                  math.cos(math.radians(current_lat))) * 180 / math.pi)

            # Reset longitude and move 1 kilometer up (latitude)
            current_lon = float(min_lon)
            current_lat += desired_radius / earth_radius * 180 / math.pi

        for coord in coordinates:
            # Check if the point is inside the polygon
            cordy = (coord[1], coord[0])
            if self.helpers.is_point_in_polygon(polygon, cordy):
                generated_coords.add(coord)

This is an example of a polygon:

{
  "type": "Feature",
  "properties": {},
  "geometry": {
    "coordinates": [
      [
        [
          2.6561338107105144,
          39.59548436489257
        ],
        [
          2.62735831717211,
          39.587478110591746
        ],
        [
          2.6263660587749484,
          39.56957313871746
        ],
        [
          2.66331309205961,
          39.569078212002836
        ],
        [
          2.673994461871615,
          39.579111036117354
        ],
        [
          2.6559587062871515,
          39.59409008377054
        ],
        [
          2.6561338107105144,
          39.59548436489257
        ]
      ]
    ],
    "type": "Polygon"
  }
}