Chestnut-winged Cuckoo I think. The pacing and pitch fit that species well. The song usually has a more pure tone but I have heard them with strained notes like this, like they have a sore throat. Maybe it happens more in young birds that need more practice
Here's a couple that are also slightly off-pitch:
Macaulay Library ML627781063; © u7 Liao; Lienchiang County, Taiwan
macaulaylibrary.org
Macaulay Library ML619831426; © chatchalai siasakul; Lop Buri, Thailand
macaulaylibrary.org
And this one gets the first note a bit wrong before settling into the usual song:
Macaulay Library ML635089013; © Y-Lin Qiu; Lienchiang County, Taiwan
macaulaylibrary.org