<?php
$str="Look at this [website]{http://www.stackoverflow.com} or at this [page]{http://www.google.com}";
echo preg_replace('/\[(.*?)\]\{(.*?)\}/', "<a href='$2'>$1</a>", $str);
Look at this <a href='http://www.stackoverflow.com'>website</a> or at this <a href='http://www.google.com'>page</a>
Output for 8.3.5
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
Look at this <a href='http://www.stackoverflow.com'>website</a> or at this <a href='http://www.google.com'>page</a>