When I edit a host with an existing parameter override and save it, I get:

"[\"192.168.1.1\",\"192.168.1.10\"]"
Before update to Foreman 1.9.2 saved value was:
["192.168.1.1","192.168.1.10"]

When I submit the host a second time:
"\"[\\\"192.168.1.1\\\",\\\"192.168.1.10\\\"]\""

I saw that this only happens when I try to save an array or a hash.