CodingKeys应该反映该类型的所有属性，继承Codable，不能有额外的字段。因此，您还应该添加标记并删除ctaInfo。

struct AllImage: Codable {
    let mediaReferenceID: String?
    let url: String?
    let title: String?
    let description: String?
    let icon: String?
    let tags: [TagInfo]?
    let footerSection: FooterSection?

    enum CodingKeys: String, CodingKey {
        case mediaReferenceID = "media_reference_id"
        case url, title, description, icon
        // Commented out this
        // case ctaInfo = "cta_info"
        // Add tags
        case tags = "tags"
        case footerSection = "footer_section"
    }
}

struct TagInfo : Codable {
    
}

struct FooterSection : Codable {
    
}