Discord has expanded its Hateful Conduct Policy to explicitly include prohibitions against misgendering and deadnaming in a policy update. Accompanying this policy update, Discord has also implemented a comprehensive warning system to enforce these guidelines effectively.
Twtich's rules account for off-site behavior. You can get banned on twitch for the things your say or do on other platforms. Twitter owner elon is a transphobe who allows and encourages deadnaming and misgendering.
Following the rules or customs of current twitter could very well get you banned from twtich for offsite behavior.