Assalamualaikum, I have a question regarding whether after you have prayed the fard prayer, and do supplication and tasbeeh, if you take a long time to do those, especially since it’s dhul hijja, will you get lower reward for the sunna prayers because you did them late, because you were doing supplication and tasbeeh? Jazakallah khair

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

The prescribed time for the Sunnah prayers that are performed after the obligatory ones starts right after performing the obligatory prayer and extends until the following obligatory prayer's due time starts. Whenever you perform the Sunnah prayer during that extended time interval, you earn the respective reward. Making supplication and Tasbeeh and reciting the reported Athkaar after the obligatory prayer is a great good deed that increases your reward, not decreases it, by the Will of Allah. You will earn the reward of performing the Sunnah prayer in full as long as you perform it during its prescribed time.

Allah Knows best.