Yogurt-based sauces generally do not freeze and reheat well due to separation and changes in texture, resulting in a grainy or watery consistency. It's best to avoid freezing them.
The primary reason yogurt sauces don't freeze well is the high water content in yogurt. When frozen, the water forms ice crystals. Upon thawing, these ice crystals melt, causing the yogurt to separate and become watery. The proteins in the yogurt also denature during the freezing process, leading to a grainy texture. While the sauce might still be safe to eat, the change in texture and consistency often makes it unappetizing. Some stabilizers can help, but the results are often still not ideal. It's generally better to make yogurt-based sauces fresh when you need them.
If you absolutely must freeze a yogurt-based sauce, try adding a small amount of cornstarch (about 1 teaspoon per cup of sauce) before freezing. This can help to stabilize the sauce and reduce separation upon thawing. However, be aware that the texture may still be slightly altered.