why react dev server use https automatically? - reactjs

Question

I'm trying to debug my react app built by create-react-app on mobile.
So I started app using react-script start,
and made sure all devices have same ip and port. But then the error came out when I tried to access react dev server on smartphone, and all I could see was just blank page.
I never use react-script options like HTTPS=true, but it seems like trying to request using HTTPS. Why?
This is a screenshot from android phone.
and this is my package.json.
{
"name": "client",
"version": "0.1.0",
"private": true,
"dependencies": {
"#ant-design/icons": "^4.1.0",
"#emotion/styled": "^10.0.17",
"#fortawesome/fontawesome": "^1.1.8",
"#fortawesome/fontawesome-free-solid": "^5.0.13",
"#fortawesome/react-fontawesome": "0.0.20",
"#juggle/resize-observer": "^3.2.0",
"#material-ui/core": "^1.5.1",
"#material-ui/icons": "^3.0.2",
"#material-ui/styles": "^4.4.1",
"#n8tb1t/use-scroll-position": "^1.0.43",
"#react-hook/media-query": "^1.1.1",
"antd": "^4.2.5",
"auth0-js": "^9.8.1",
"axios": "^0.18.1",
"core-js": "^3.6.5",
"d3-ease": "^1.0.6",
"emotion": "^9.2.12",
"env-cmd": "^10.1.0",
"fast-deep-equal": "^2.0.1",
"formik": "^1.5.8",
"formik-effect": "^1.2.0",
"i18next": "^17.0.14",
"i18next-browser-languagedetector": "^3.0.3",
"i18next-xhr-backend": "^3.1.2",
"immutable": "^4.0.0-rc.12",
"jquery": "^3.5.1",
"js-cookie": "^2.2.0",
"jsonwebtoken": "^8.3.0",
"lodash": "^4.17.15",
"mapbox-gl": "^1.10.1",
"materialize-css": "^1.0.0-rc.2",
"moment": "^2.24.0",
"randomstring": "^1.1.5",
"react": "^16.10.2",
"react-app-polyfill": "^1.0.2",
"react-awesome-modal": "^2.0.5",
"react-circular-progressbar": "^2.0.3",
"react-countup": "^4.2.2",
"react-currency-input": "^1.3.6",
"react-dom": "^16.10.2",
"react-dropdown-tree-select": "^2.1.0",
"react-dropzone": "^4.2.12",
"react-emotion": "^9.2.12",
"react-flags-select": "^1.1.10",
"react-ga": "^2.7.0",
"react-google-login": "^5.0.4",
"react-google-maps": "^9.4.5",
"react-highcharts": "^16.0.2",
"react-i18next": "^10.12.3",
"react-iamport": "0.0.2",
"react-icons": "^3.7.0",
"react-images": "^0.5.17",
"react-map-gl": "^5.2.5",
"react-materialize": "^3.3.1",
"react-moment": "^0.7.7",
"react-move": "^6.4.0",
"react-paginate": "^6.3.0",
"react-password-strength": "^2.4.0",
"react-quill": "^1.3.3",
"react-redux": "^7.1.0-rc.1",
"react-responsive-carousel": "^3.1.50",
"react-reveal": "^1.2.2",
"react-router-dom": "^5.2.0",
"react-router-hash-link": "^1.2.2",
"react-scripts": "^3.4.1",
"react-share": "^3.0.0",
"react-slick": "^0.23.2",
"react-sortable-hoc": "^1.11.0",
"react-sticky": "^6.0.3",
"react-tooltip": "^3.11.1",
"react-transition-group": "^4.3.0",
"react-treebeard": "^3.2.4",
"react-typed": "^1.1.2",
"react-use-measure": "^2.0.1",
"redux": "^4.0.0",
"redux-actions": "^2.6.5",
"redux-promise": "^0.6.0",
"redux-saga": "^1.1.3",
"redux-thunk": "^2.3.0",
"regenerator-runtime": "^0.13.7",
"slick-carousel": "^1.8.1",
"socket.io-client": "^2.2.0",
"styled-components": "^4.3.2",
"universal-cookie": "^3.1.0",
"uuid": "^3.3.2",
"yup": "^0.27.0"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"build:dev": "env-cmd -f ./.env.dev react-scripts build",
"build:prod": "env-cmd -f ./.env.prod react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},
"eslintConfig": {
"extends": "react-app"
},
"browserslist": {
"production": [
">0.2%",
"not dead",
"not op_mini all"
],
"development": [
"last 1 chrome version",
"last 1 firefox version",
"last 1 safari version"
]
},
"devDependencies": {
"http-proxy-middleware": "^0.19.1",
"react-test-renderer": "^16.9.0",
"typescript": "^3.9.6"
}
}