In Internet communities such as forums and social media, users can change their nicknames or avatars, which is sometimes called "changing waistcoats". This statement comes from China ancient opera, and actors need to wear different vests to play different roles. Therefore, "changing waistcoat" has no derogatory or insulting meaning in this sense.

However, in some contexts, "changing waistcoats" may mean belittling or implying insult. For example, someone who acts under a false identity or conceals his true identity may be described as "changing his waistcoat". In this context, "changing waistcoat" may mean cheating, disguising or hiding one's true identity, which has certain derogatory meaning and ambiguity.

Therefore, whether there will be ambiguity depends on the specific context and the listener's understanding. When someone says that someone is "changing his vest", make sure that all relevant personnel know its meaning and intention.