If someone misses Fajr unintentionally and wakes up after sunrise but sleeps again deliberately and prays it later, will his prayer be valid, will he come under the same ruling as whom scholars have said about that deliberately missing the prayer or this matter is a little broader in scope (as he deliberately didn't sleep till sunrise) ?

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 prayer of this person is valid but the question here is: is he sinful by delaying making it up after he woke up? This depends on the preponderant view of the majority of the jurists on the ruling of making up for a missed prayer with an excuse, and whether it has to be immediately or that one can take his time to make it up? The majority of the jurists are of the view that one is obliged to make up for a missed prayer immediately and that it is forbidden to delay making it up. However, the Shaafi'i School is of the view that making up a prayer immediately is desirable but not an obligation.

The Fiqh Encyclopedia reads:

“The majority of the jurists are of the view that if one forgets a prayer or sleeps through its time, then he is obliged to make it up immediately and it is forbidden to delay it, as the Prophet said: “If one of you forgets a prayer or sleeps through its time, he should pray it as soon as he remembers it.”

So the Prophet ordered to make up the prayer when one remembers it; the order entails an obligation. The majority of the jurists are of the view that it is with greater reason that it refers to the abandonment of the prayer due to sleep or forgetfulness in regard to the obligation of making up a prayer. According to them, it is permissible to delay making up a missed prayer for a valid purpose, such as eating, drinking, and necessary sleeping, and answering the call of nature, and obtaining what one needs in his livelihood.

The Shaafi'i School excluded abandoning the prayer for an excuse; it is desirable for the person to make it up immediately, and if he delays it, then it is permissible, as it was reported that the Prophet missed the Fajr prayer and he did not make it up until he left the valley in which he was. They said: "If it was an obligation to make it up immediately, he would not have delayed it.”

For more benefit, please refer to Fataawa 283681 and 89978.

Allah knows best.