Security Recommendations around https://www.w3.org/TR/2010/WD-html5-20100624/the-iframe-element.html

Hello,
I noted a security flaw in a implementation scenario in iframe sandboxes
https://www.w3.org/TR/2010/WD-html5-20100624/the-iframe-element.html
which does not currently appear to be documented as a risk.
More info:
https://blog.analyzenothing.com/2019/10/html-sandboxes-restrictions-bypass-forms.html

Could i recommend adding in a warning into the documentation about such a
risk?
Thanks