ESI for dynamic content with Elementor PRO

is it a shortcode or block or something ?

have you checked this ?

well, basically , the idea on that is , whenever you were trying to display something , you convert it into a separated request and use ESI to insert into the main page

for example in normal way , I want to display a random number in my header , then I can do something like this

<div><?php
echo rand (1,99999);
?>
</div>

with ESI , move that PHP code into function , make it like

<div>
<?php
echo apply_filters( 'litespeed_esi_url', 'my_esi_block', 'Custom ESI block' );
?>
</div>

to call the function , then code the function to display the random number , e.g.

add_action( 'litespeed_esi_load-my_esi_block', 'my_esi_block_esi_load' );

function my_esi_block_esi_load()
{
do_action( 'litespeed_control_set_nocache' );
echo "Hello world".rand (1,99999);
}