If a Muslim prays with the congregation, in Ramadhan, the Taraweeh prayer and there is also a prayer in the last third of the night, then which of the two is better and takes precedence? To perform the witr with the congregation and make the witr even, or should he leave off the witr with the congregation and pray the witr in last third?

It is better to complete the prayer with the Imam as Allah legislated, because the prophet (sallallaahu alaihi wa sallam) said, Verily, when a man prays with the Imam until the imams (finishes) and departs, Allah writes (for him the reward) of (praying) the rest of the night.

And that is because when he (may Allah raise his rank and status) led the companions [in taraweeh], up to a third of the night some nights, and in some they prayed up to half of the night, they asked,

“O Messenger of Allah, (what) if we pray (more) optional prayers for the rest of our night; he replied Verily, when a man prays with the Imam until the imams (finishes) and departs, Allah writes (for him the reward) of (praying) the rest of the night.

This is what is better, that he continues with the Imam including the witr and if he prays in the last third the first witr suffices him, there is no need to perform a second witr, All praises belong to Allah, he would perform witr with the Imam and pray what he is able in the last third even number, (ie 2 by 2) without a witr, yes. As has preceded in the first question.

Questioner: If he prayed witr with the imam and then made it even and prayed witr in the last third?

Shaykh:
If he makes it even, then no problem… When the Imam gives the salaam, then he stands and adds a rakah to make it even and performs the witr in the last third, no problem.

However this could possibly become difficult for the souls and it might be feared that the person who does this could be considered to show off.

In conclusion, if he suffices with the witr (with the Imam), All praises belong to Allah it suffices. And if he makes it even then no issue, if he makes it even and performs witr in the last third, then no problem. And if he suffices with the witr and then prays in the last third that which is easy for him, 2 units of prayer, or 4 or 6 or 8 etc then no problem, there is no need for (another) witr the first witr suffices him. Yes.

https://binbaz.org.sa/fatwas/5874/حكم-صلاة-الوتر-مع-امام-التراويح-او-تركه-الى-اخر-الليل