

Presuming you have not limited edge port 22 to one or two IPS and that you are not translating a high port to 22 internal, the danger is that you are allowing the entire internet to hammer away at your ssh. If you have this described setup, you will most definitely see the evidence of attempts to break in in your SSH endpoint and firewall logs.
Zero days for SSH do exist, so it’s just a matter of time before you’re compromised if you leave this open.
Is your container isolated from your internal network?
If I were to compromise your container, I’d immediately pivot to other systems on your private network.
Why do the difficult thing of breaking out of a container when there’s a good chance I can use the credentials I got breaking in to your container to access other systems on your network?