Extendscript timeRemap values changing after changing layer startTime

layer = app.project.activeItem.layer(1)
timeRemapProp = layer.property("ADBE Time Remapping");
timeRemapProp.removeKey(2)
tvalues = [0,1,1.5];
times = [0,1,6];
timeRemapProp.setValuesAtTimes(tvalues, times);

It set time correctly, but than i want to change startTime of layer:

layer.startTime = 10;

Everyting is fine

layer.startTime = 30;

After this second keyframe time changes to 0.5 second (should remain 1) and 3rd to 5.5second (should be 6)

https://youtu.be/k3-M94R7z7s

Any ideas why that happening?