Taxonomy Reference Field entity autocomplete is not working

This is not, in general, broken so we need more detailed steps to reproduce.

We need more information on the bug than what you provided. You described ordinary setups that usually work.

Autocomplete values are not populating after upgradation in Drupal 10.2.3 and it is keep on searching.
In network tab i am getting AJAx response with results but front it is not populating.

We need more information for a bug report.

Autocomplete suggestions are not displaying while searching any keyword but in json response i am getting suggestions but it is not displaying in front end.

does it happen on the claro admin theme? I see you're still using seven here which is now a contrib module.

In JSON response it is missing closing bracket and not valid JSON is returned.
[
{
"value": "AdvanceFlow API (985)",
"label": "AdvanceFlow API"
},
{
"value": "API Platform Tools (989)",
"label": "API Platform Tools"
},
{
"value": "CCPA (986)",
"label": "CCPA"
},
{
"value": "CUAS (1001)",
"label": "CUAS"
}

After upgradation to 10.2.3 onwards it is returning not valid JSON data.

What is the platform and web server setup?

Pantheon web server we are using

What are the headers on that broken Ajax response?

Does Drupal or the web server log an error on the server side?

Have you been in touch with Pantheon support?

Refer here it is fixed the issue : https://www.drupal.org/project/drupal/issues/3409885 🐛 Uncaught ajax.js error / exception Active