"become liable to" is a phrase that is commonly used to describe a situation in which someone or something is at risk of facing negative consequences. Essentially, it means that there is a possibility that something bad may happen if certain conditions are not met or if certain actions are taken. To find synonyms for this phrase, one could look for words that convey a sense of responsibility or potential harm. Some examples might include "subject to," "vulnerable to," "exposed to," "open to," "prone to," or "liable for." Each of these phrases has a slightly different connotation, but they all suggest that there is a risk or danger that needs to be considered and addressed.