The cause is not known yet. Build1 causes 503 errors with runaway lsphp processes. It may only affect centos7/cloudlinux servers with litespeed. The fix is downgrading to build 0
/usr/local/lsws/admin/misc/lsup.sh -f -v 5.3.7 -b 0; killall litespeed lsphp; /usr/local/lsws/bin/lswsctrl restart
/usr/local/lsws/admin/misc/lsup.sh -f -v 5.3.7 -b 0; killall litespeed lsphp; /usr/local/lsws/bin/lswsctrl restart