<?php
$body = "
""  
<h1>?</h1> 
<img src="https://example.com/test.jpg" title=""/>
";

    $keywords = [
       ["id"=>1,"title"=>"","url"=>"https://www.example.com/gaimingzi.html"],
       ["id"=>2,"title"=>"","url"=>"https://www.example.com/mingzi.html"],
       ["id"=>3,"title"=>"","url"=>"https://www.example.com/duanshipin.html"],
    ];
foreach ($keywords as $keyword)
{
   $body = preg_replace("/(>[^<>]*?)(" . $keyword["title"] . ")([^<>]*?<)/", "$1<a href="". $keyword["url"]. "" target="_blank">$2</a>$3", $body,1);
}

echo $body;

from the tags database. When adding articles, there is no processing of keywords, only in the article details page to do the above processing.