Is a woman for whom separation has occurred between her and her husband due to the marriage being invalid or void entitled to a compensatory gift (mut'ah), and what is the evidence for that?

A فاسد (corrupt/invalid) marriage, after consummation, entails the rulings of a valid marriage, including the obligation of mut'ah (a compensatory gift). The details of mut'ah vary depending on the reason for separation. If the separation is due to the wife, she is not entitled to mut'ah. If it is due to the husband or a third party (such as fosterage), mut'ah becomes obligatory in some cases and is waived in others, depending on whether the contract specified a dowry or not, and whether the separation occurred before or after consummation. The cases in which mut'ah is usually waived are those where the separation is due to the woman (such as her apostasy, her conversion to Islam, or her choice to annul the marriage due to a defect in her).