Expected behaviour of overlayfs?

I'm trying to build a merged overlay structure where i can replace(offline, even with reboot) the lower layer. Somehow it is not working as expected to demonstrate my problem i used the following example:

mkdir lower upper work mergedmount -t overlay overlay -o lowerdir=lower,upperdir=upper,workdir=work mergedmkdir merged/testgetfattr -n trusted.overlay.opaque upper/testumount mergedmkdir -p lower/testtouch lower/test/blub.txtmount -t overlay overlay -o lowerdir=lower,upperdir=upper,workdir=work mergedls -la merged/testumount mergedtouch upper/test/bla.txtmount -t overlay overlay -o lowerdir=lower,upperdir=upper,workdir=work mergedls -la merged/testumount mergedrm -rf lower upper work merged

with following results:

sh:/data# umount mergedsh:/data# mkdir -p lower/testsh:/data# touch lower/test/blub.txtsh:/data# mount -t overlay overlay -o lowerdir=lower,upperdir=upper,workdir=work mergedsh:/data# ls -la merged/testtotal 8drwxr-xr-x 2 root root 4096 Feb  3 16:58 .drwxr-xr-x 1 root root 4096 Feb  3 16:58 ..sh:/data# umount mergedsh:/data# touch upper/test/bla.txtsh:/data# mount -t overlay overlay -o lowerdir=lower,upperdir=upper,workdir=work mergedsh:/data# ls -la merged/testtotal 8drwxr-xr-x 2 root root 4096 Feb  3 16:58 .drwxr-xr-x 1 root root 4096 Feb  3 16:58 ..-rw-r--r-- 1 root root    0 Feb  3 16:58 bla.txtsh:/data# umount mergedsh:/data# rm -rf lower upper work merged

So basically I create a new folder on the empty merged overlayfs. As expected it creates this directory in the upper layer. But with the "trusted.overlay.opaque" set?

Now with that attribute set my changes on the lower filesystem will be hidden in the future. The changes are done offline so it should be valid?

tested on debian(4.19 kernel) and archlinux(5.10 kernel)

thank you for your time :)