see if pm.max_children alert was called
grep max_children /var/log/php?.?-fpm.log.1 /var/log/php?.?-fpm.log
find processes size to determine pm.max_chilrden = memory / result (custom 512 value)
ps --no-headers -o "rss,cmd" -C php-fpm7.3 | awk '{ sum+=$1 } END { printf ("%d%s\n", sum/NR/512,"M") }'