global variable in .module not seen

Hello everybody
I cant understand why my global isn’t seen anywhere : I’ve got a form class, and a .module. Into the .module I wrote :

$lol= 'test';
use DrupalCoreTemplateAttribute;

function mymodule_theme_fx_links($variables) {
  global $lol;
  ksm($lol); // prints NULL
...

If I try from the class : NULL, as well.
What do I miss ?

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