Log flooded with mautic.NOTICE: PHP Notice - Trying to access array offset on value of type bool - Redlining Server

we just upgraded a problematic instance to 4.1.0 following my investigation in this post.
And now I see the same message coming up all the time

2021/12/19 14:05:11 [error] 1075139#1075139: *100 FastCGI sent in stderr: "PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in
 /var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in 
/var/www/mautic/plugins/MauticFocusBundle/Include/lessc.inc.php on line 719PHP message: PHP 
Notice:  Trying to access array offset on value of type bool in /var/www/mautic/plu