High shares memory usage

Hello y'all,

My monitoring tools started showing my Unraid server was using a lot of shared memory. Here is the chart from the last 24 hours (with the server mostly idling):

So, I did a little bit of search on the web and tried the following:

root@server:~# free -m
              total        used        free      shared  buff/cache   available
Mem:          64191       30582       18970       13022       14638       19920
Swap:             0           0           0

root@server:~# ipcs -m
------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status

Not much to see here, except I do see there are indeed 12+ GB worth of shared memory. I then stumbled upon the following post (https://stackoverflow.com/a/40712727/1689179) and script:

cd /proc
for i in `ls -d * | grep -v self`
do 
  if [[ -f $i/statm ]];then 
     echo -n "$i "; cat $i/statm | perl -lan -e 'print ($F[2] * 4096)'; 
  fi  
done | sort -nr -k2 | head

I got the following results:

root@server:~# sh test
1034 49528832
19397 30261248
2919 29437952
1445 26116096
1062 24440832
5986 23838720
5598 23777280
5807 23760896
6567 23732224
6266 23629824

root@server:~# ps -p 1034 -p 19397 -p 2919 -p 25669 -p 1062 -p 5986 -p 5598 -p 5807 -p 6567 -p 6266
  PID TTY          TIME CMD
 1034 ?        03:52:53 dockerd
 1062 ?        01:44:31 containerd
 2919 ?        00:08:48 mono-sgen
 5598 ?        04:03:06 qemu-system-x86
 5807 ?        15:12:03 qemu-system-x86
 5986 ?        15:52:44 qemu-system-x86
 6266 ?        2-19:39:15 qemu-system-x86
 6567 ?        04:24:21 qemu-system-x86
19397 ?        00:41:01 Plex Media Serv

So dockerd/containerd and qemu. I don't see anything relevant in the logs... what could have triggered the sudden raise of shared memory usage?