Lazarus was dead 4 days. There is no record of him seeing anything during that time. You are not dead until the blood is dead.
Scripture records no words from Lazarus—neither direct statements nor indirect references to anything he might have said.
Maybe Lazarus thought that what happened in his experience, was something that it wasn’t his place to share with others. Some things are beyond our human ability to describe. If he spent that much time in “the great beyond” after he passed, it could be that he knows what he saw but he wasn’t ready to share what he saw. Just something I’ve pondered over the years.