Please do keep us up to date on your latest test results having bumped those limits! Obviously I realize you have only seen issues on the RPi4 after a few days, so these results may take some time.
As an additional idea, you may be able to load some proper metrics collectors like netdata/datadog/telegraf/node_exporter to better understand what leads up to these memory alloc issues. We have published a few blog posts on how to set these up (and other users have contributed some great forums posts!), see: