Is the Hajj valid or void if the taqseer (shortening of hair) was not performed after the Umrah before entering into ihram for Hajj, and forbidden acts of ihram, such as clipping nails, were committed?

Doubt regarding an action after its completion does not affect its validity. So, if the sister doubts her 'Umrah and Hajj after completing them, her acts of worship are valid.

However, if the sister is certain that she entered into the state of ihram for Hajj before exiting the state of ihram for 'Umrah, there is a difference of opinion among jurists on this matter: - Some scholars are of the view that it is not valid to combine Hajj with 'Umrah after beginning its circumambulation (tawaf). - Maliki jurists provided a detailed explanation: It is permissible to combine Hajj with 'Umrah after the sa'i and before shaving (or cutting the hair). Her ihram would be valid, and she would owe a sacrifice (hady) for delaying the shaving/cutting of hair for 'Umrah. - The Shafi'is and Hanbalis hold that it is not valid to combine Hajj with 'Umrah after the tawaf and sa'i. However, the Hanbalis made an exception for those who have a sacrificial animal (hady) with them.

Based on this, the sister's Hajj and 'Umrah are valid according to the Maliki school of thought. She owes a fidyah (expiation) for the prohibitions of ihram that she committed (such as cutting nails), and a dam (blood sacrifice) for delaying the shaving/cutting of hair for 'Umrah. This is all if she is certain about having omitted the shortening of hair (taqseer). However, if it is merely a doubt, her acts of worship are valid.