Peace be upon you and God's mercy and blessings. According to Grand Ayatollah Sayyid Sistani (may God protect him): If a woman experiences a discharge that is not blood, even if it has a yellowish tint, it is considered pure and does not invalidate the fast. Source: [Official Website](https://www.sistani.org/arabic/qa/4909/). According to Grand Ayatollah Sayyid Khamenei (may God protect him): As long as she is not certain about the impurity of this discharge, it is considered pure, and there is no need to remove it, nor does it invalidate the fast. Source: [Special Inquiry](https://islamq2a.com/masdar/326.jpg). May you be successful in all good.