When expressing doubt or uncertainty about something, there are various synonyms that can be used instead of the phrase "bringing in to question." Some options include "casting doubt," "raising concerns," "calling into doubt," "questioning the validity of," and "challenging." Each of these phrases conveys a sense of skepticism or inquiry, highlighting a need for further investigation or clarification. Depending on the context and tone of the communication, different synonyms may be more appropriate. Overall, using precise and varied language can help convey a nuanced message and avoid repetition.