PHP doesn't show images in WKWebView

Since httpRequest body is ignored on WKWebView, I am trying to display a php page by fetching the data first, and displaying it.

func fetchData() {
    URLSession.shared.dataTask(with: request) {(data, response, error) in
            guard let data, let url = request.url else {
                return
            }
            // pass the result to WKWebView
        }.resume()
}

import Foundation
import SwiftUI
import WebKit

struct CustomWebView: UIViewRepresentable {
    
    var url: URL
    var data: Data
        
    func makeUIView(context: Context) -> UIView {
        return CustomUIWebView(url: url, data: data)
    }
}

class CustomUIWebView: UIView {
    
    let webView: WKWebView
    
    init(url: URL,data:Data) {
        let webConfiguration = WKWebViewConfiguration()
        webView = WKWebView(frame: .zero, configuration: webConfiguration)
        super.init(frame: .zero)
        webView.load(data, mimeType: "text/html", characterEncodingName: "utf-8", baseURL: url)
        addSubview(webView)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        webView.frame = bounds
    }

The data contains the page that display several images, but it doesn't display any of the images in WKWebView. Test and other components (such as checkmark button) have no problem, only images do. Also, I confirmed it works fine on Safari.

So what is the issue here? What am I doing wrong?