Is ghusl required upon seeing small spots on one's garment resembling semen, without feeling nocturnal emission or anything exiting, especially with the possibility of madhiy (pre-seminal fluid) exiting and being felt, particularly given one's suffering from scrupulosity regarding wudu and ghusl?

Ghusl is not obligatory as long as one is certain they did not have a wet dream, especially if they are experiencing obsessive thoughts (waswas). If they predominantly think some drops were discharged, these are madhiy (pre-seminal fluid), which is impure and requires cleansing the clothes, but it does not necessitate ghusl.