The same issue is happening to me.
I have a server running Kibana 7.3 on OpenJDK11, Aws Ubuntu 18.04 instance with 4GB ram and with 2GB allocated to elasticsearch.
It is running the marvel monitor on a simple 3 node cluster also running 7.3
If I just watch the Kibana app monitoring summary screen for a few minutes it kills elasticsearch with the error as per the first poster.
All commands to elasticsearch fail at this point with circuit_breaking_exceptions.
kibana elasticsearch has the following limited indexes at that point.
green open .monitoring-es-7-2019.08.01 G0mV0MbkTkyenmcbx-_0IA 1 0 2535 1904 2.6mb 2.6mb
green open .kibana_1 N47OPCEaQFyIpX1bn6X86w 1 0 4 0 15.3kb 15.3kb
Eventually the server recovers until I look at the screen again at which point it fails.
The server is completely new install that has only been running for 30 minutes.
There's practically nothing going on I can't imagine I should be having memory issues.
Making the change Magnus suggests seems to fix the issue.
i.e. XX:-UseG1GC , XX:+UseConcMarkSweepGC