Is it necessary to perform ghusl upon waking up if there are spots on one's garment and one is not certain whether they are semen, madhiy, or bleach stains resulting from washing the garment?

If you doubt the nature of spots you see on your garment, whether they are pure or impure, consider them pure. This is because the default state of things is purity until impurity is established with certainty. Similarly, you are not required to perform ghusl (ritual bathing), because the reason for its obligation—which is the emission of semen—is doubtful. The default state is that ghusl is not obligatory until its cause is established with certainty.