<?php
$line="This is the first test.{@font-face:Garamond}";
preg_match("/(?<=.{1})(?<![\]\\])\{([\w\s\\@:=\'\"-\.;^}]*)(?<=.{1})(?<!\\)\}/", $line, $array);
var_dump($array);
Warning: preg_match(): Compilation failed: missing closing parenthesis at offset 60 in /in/ItTMB on line 3
NULL
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
Warning: preg_match(): Compilation failed: missing closing parenthesis at offset 60 in /in/ItTMB on line 3
NULL