net/netfilter/nf_conntrack_standalone.c in the Linux kernel before 5.12.2 allows observation of changes in any net namespace because these changes are leaked into all other net namespaces. This is related to the NF_SYSCTL_CT_MAX, NF_SYSCTL_CT_EXPECT_MAX, and NF_SYSCTL_CT_BUCKETS sysctls.
Image SLES15-SP3-Manager-4-2-Proxy-BYOS-Azure Image SLES15-SP3-Manager-4-2-Proxy-BYOS-EC2-HVM Image SLES15-SP3-Manager-4-2-Proxy-BYOS-GCE Image SLES15-SP3-Manager-4-2-Server-BYOS-Azure Image SLES15-SP3-Manager-4-2-Server-BYOS-EC2-HVM Image SLES15-SP3-Manager-4-2-Server-BYOS-GCE openSUSE Leap 15.3 openSUSE Leap 15.4 SUSE CaaS Platform 4.0 SUSE Enterprise Storage 6 SUSE Enterprise Storage 7 SUSE Linux Enterprise Desktop 15 SP2 SUSE Linux Enterprise Desktop 15 SP3 SUSE Linux Enterprise Desktop 15 SP4 SUSE Linux Enterprise Desktop 15 SP5 SUSE Linux Enterprise High Availability 15 SP3 SUSE Linux Enterprise High Performance Computing 12 SP5 SUSE Linux Enterprise High Performance Computing 15 SUSE Linux Enterprise High Performance Computing 15 SP1 SUSE Linux Enterprise High Performance Computing 15 SP2 SUSE Linux Enterprise High Performance Computing 15 SP3 SUSE Linux Enterprise High Performance Computing 15 SP4 SUSE Linux Enterprise High Performance Computing 15 SP5 SUSE Linux Enterprise Micro 5.0 SUSE Linux Enterprise Micro 5.1 SUSE Linux Enterprise Micro 5.2 SUSE Linux Enterprise Module for Basesystem 15 SP2 SUSE Linux Enterprise Module for Basesystem 15 SP3 SUSE Linux Enterprise Module for Basesystem 15 SP4 SUSE Linux Enterprise Module for Basesystem 15 SP5 SUSE Linux Enterprise Module for Development Tools 15 SP2 SUSE Linux Enterprise Module for Development Tools 15 SP3 SUSE Linux Enterprise Module for Development Tools 15 SP4 SUSE Linux Enterprise Module for Development Tools 15 SP5 SUSE Linux Enterprise Module for Legacy 15 SP3 SUSE Linux Enterprise Module for Legacy 15 SP4 SUSE Linux Enterprise Module for Legacy 15 SP5 SUSE Linux Enterprise Module for Live Patching 15 SP3 SUSE Linux Enterprise Module for Public Cloud 15 SUSE Linux Enterprise Module for Public Cloud 15 SP1 SUSE Linux Enterprise Module for Public Cloud 15 SP3 SUSE Linux Enterprise Module for Public Cloud 15 SP4 SUSE Linux Enterprise Real Time 15 SP2 SUSE Linux Enterprise Server 12 SP5 SUSE Linux Enterprise Server 15 SUSE Linux Enterprise Server 15 SP1 SUSE Linux Enterprise Server 15 SP2 SUSE Linux Enterprise Server 15 SP3 SUSE Linux Enterprise Server 15 SP4 SUSE Linux Enterprise Server 15 SP5 SUSE Linux Enterprise Server for SAP Applications 12 SP3 SUSE Linux Enterprise Server for SAP Applications 12 SP4 SUSE Linux Enterprise Server for SAP Applications 12 SP5 SUSE Linux Enterprise Server for SAP Applications 15 SUSE Linux Enterprise Server for SAP Applications 15 SP1 SUSE Linux Enterprise Server for SAP Applications 15 SP2 SUSE Linux Enterprise Server for SAP Applications 15 SP3 SUSE Linux Enterprise Server for SAP Applications 15 SP4 SUSE Linux Enterprise Server for SAP Applications 15 SP5 SUSE Linux Enterprise Storage 6 SUSE Linux Enterprise Storage 7 SUSE Linux Enterprise Storage 7.1 SUSE Linux Enterprise Workstation Extension 15 SP3 SUSE Linux Enterprise Workstation Extension 15 SP4 SUSE Manager Proxy 4.0 SUSE Manager Proxy 4.1 SUSE Manager Proxy 4.2 SUSE Manager Proxy 4.3 SUSE Manager Retail Branch Server 4.0 SUSE Manager Retail Branch Server 4.1 SUSE Manager Retail Branch Server 4.2 SUSE Manager Retail Branch Server 4.3 SUSE Manager Server 4.0 SUSE Manager Server 4.1 SUSE Manager Server 4.2 SUSE Manager Server 4.3 SUSE OpenStack Cloud 8 SUSE OpenStack Cloud 9 SUSE OpenStack Cloud Crowbar 8 SUSE OpenStack Cloud Crowbar 9