Override HTTP responses from a Chrome extension - google-chrome

Question

I'm making an extension that will be able to modify request responses. I did some research, found this answer https://stackoverflow.com/a/51594799/16661157 and implemented it into my extension.
When debugging this script, it detects the majority of requests but not all, unfortunately the most important for me are not. So my question is: what could be causing this?
manifest.json
{
"manifest_version": 3,
"permissions": [
"tabs"
],
"web_accessible_resources": [{
"resources": ["script.js"],
"matches": [ "<all_urls>" ]
}],
"action": {
"default_popup": "index.html"
},
"content_scripts": [
{
"matches": [ "<all_urls>" ],
"js": ["jquery-3.6.0.min.js", "contentscript.js"],
"run_at": "document_start"
}
]
}
contentscript.js
var s = document.createElement('script');
s.src = chrome.runtime.getURL('script.js');
s.onload = function() {
this.remove();
};
(document.head || document.documentElement).appendChild(s);
script.js
var _open = XMLHttpRequest.prototype.open;
window.XMLHttpRequest.prototype.open = function (method, URL) {
var _onreadystatechange = this.onreadystatechange,
_this = this;
_this.onreadystatechange = function () {
// catch only completed 'api/search/universal' requests
try {
console.log('Caught! :)', method, URL/*, _this.responseText*/);
} catch (e) {}
if (_this.readyState === 4 && _this.status === 200 && ~URL.indexOf('api/search/universal')) {
try {
//////////////////////////////////////
// THIS IS ACTIONS FOR YOUR REQUEST //
// EXAMPLE: //
//////////////////////////////////////
var data = JSON.parse(_this.responseText); // {"fields": ["a","b"]}
if (data.fields) {
data.fields.push('c','d');
}
// rewrite responseText
Object.defineProperty(_this, 'responseText', {value: JSON.stringify(data)});
/////////////// END //////////////////
} catch (e) {}
}
// call original callback
if (_onreadystatechange) _onreadystatechange.apply(this, arguments);
};
// detect any onreadystatechange changing
Object.defineProperty(this, "onreadystatechange", {
get: function () {
return _onreadystatechange;
},
set: function (value) {
_onreadystatechange = value;
}
});
return _open.apply(_this, arguments);
};