During the mausoleum scene Leta reveals the Lestrange family tree whilst recounting the events of what happened to Corvus. I had the impression that as the family tree was growing it was developing into its current form and that is why the Corvus node withered at the end rather than straight away. However, on a recent answer of mine a user commented that they thought that Leta had actually withered the tree.
Looking into The Official Screenplay we have very little information unfortunately.
SCENE 104
INT. LESTRANGE MAUSOLEUM—NIGHT[...]
LETA: Corvus Lestrange is already dead. I killed him.
LETA raises her wand.
LETA: Accio!
A heavy box, hidden in the corner of the mausoleum, comes crashing to her through the dust. A series of clicks as cogs whirr... Puzzle-like, it falls apart.
LETA: My father owned a very strange family tree. It only recorded the men...
We glimpse a tree with an orchid-like flower twisting around it.
LETA: ...the women in my family were recorded as flowers. Beautiful. Separate.
[...]
SCENE 110
INT. LESTRANGE MAUSOLEUM—NIGHT...the drowning baby falling through sea-green light, hanging in the air in the mausoleum. LETA has conjured it. It has haunted her all her life and now she shows it to them.
The orchid representing LETA on the Lestrange family tree twists around the branch labeled CORVUS LESTRANGE until the leaves wither and die.
Fantastic Beasts: The Crimes of Grindelwald - The Original Screenplay
Now it could just be very convenient timing that the story ended when it did in time to show the Corvus node withering or Leta could have done it. What caused the Corvus node on the family tree to wither and die?
Whilst this may or may not be answered in the upcoming films (depends on Credence really), I am mainly looking for information we have now. For example, it's been a while since I've seen the film, maybe something was shown more explicit in it to what happened and I can't remember. There could also be interviews and tweets on this to look into.