But Star Wars Rebels made it clear there were other Holocrons out there, hidden and never recovered by Palpatine.
Thus it’s likely most of the Sith Holocrons were lost.
Hear this out loudPauseThe Sith Can Be Reborn Through Holocrons The Sith may have been destroyed, but they left an indelible mark on the galaxy. Are there any Sith left after rise of Skywalker? Some time prior to 3998 BBY, the young Onderonian metallurgist Shas Dovos made his own suit of Sith armor out of steel plates, following the instruction of an ancient book. Hear this out loudPauseThe Sith armors traditionally consisted of metal plates worn over dark robes, and were usually covered in sharp spines to be used as weapons.