Chrome Extension background.js not receiving message sent from content.js - google-chrome

Question

I want to send data from my inject.js to background.js so that it calls for an external API to store the data into DB.
Here are my sample files
manifest.json
{
"name": "Income Tax Notice Reader",
"description": "Reads Income Tax notices once you login into the IT account",
"version": "1.0",
"manifest_version": 3,
"permissions": [
"alarms",
"notifications",
"activeTab",
"tabs",
"storage",
"scripting"
],
"background": {
"service_worker": "background.js"
},
"content_scripts": [{
"exclude_globs": [
"chrome://extensions/"
],
"matches": [
"<all_urls>"
],
"all_frames": true,
"js": ["jquery.min.js","content.js"]
}],
"web_accessible_resources": [{
"resources": ["inject.js","jquery.min.js"],
"matches": [ "<all_urls>" ]
}],
"action": {},
"icons": {
"16": "favicon.ico"
},
"commands":{
"_execute_browser_action": {
"suggested_key": {
"default": "Ctrl+Shift+F",
"mac": "MacCtrl+Shift+F"
}
}
}
}
My content.js file
var script = document.createElement('script');
script.src = chrome.runtime.getURL('jquery.min.js');
(document.head||document.documentElement).appendChild(script);
var script = document.createElement('script');
script.src = chrome.runtime.getURL('inject.js');
(document.head||document.documentElement).appendChild(script);
window.addEventListener("message",function(event){
alert(event.data.message);
chrome.runtime.sendMessage(event.data);
return true;
});
Background.js
chrome.tabs.onUpdated.addListener( function (tabId, changeInfo, tab) {
if (changeInfo.status == 'complete') {
chrome.scripting.executeScript({
target: {tabId: tab.id},
files: ['content.js']
});
}
})
chrome.runtime.onMessage.addListener(function(event){
console.log(event.data.message);
return true;
});
inject.js
window.postMessage({message:"send message to background worker"});
The message is reaching till content.js, but it is not going from content.js to background.js, not sure what I am doing wrong here, tried multiple ways but still failing to understand the issue.