Thanks for you answer,
… gtm4wc was not the issue ??
After some investigations, the way Uncode theme is managing the woocommerce hook “woocommerce_before_shop_loop_item” was a bit strange.
Even with a simple echo “test” i got the same issue.
=> i’ve decided to use a hook inside the product of the loop of products, by changing line 2285 of woocemmerce.php of gtm4wc with this hook call : woocommerce_before_shop_loop_item_title
And “_title” did the trick ?? the span is now included, close to the title in the loop without interfering with the layout builder of Uncode