Firstly, ejaculation itself is not necessarily problematic for health. There's a lot of research that shows benefits for prostate health, as well as stress relief, and even some reports of blood circulation improvements.
The issue isn't the impact on the body, though, but the brain. Due to the releases of dopamine, it can make us numb to other sources of joy. Occasional masturbation is not necessarily harmful, however, in high levels of frequency it can impact how we experience pleasure and satisfaction. Food won't taste as good, hobbies won't be as entertaining, and long form entertainment (reading books, watching 2 hour movies, long conversations in person instead of text, etc) will not be as easy to engage in compared to TikTok and other more immediate pleasures.
To your initial point, however, defining excessive varies based on the person. 2-3 times per week is not necessarily abnormal for the window of late adolescence or early adulthood. If you find you start having motivation challenges, symptoms of depression, fatigue, or excessive boredom, it may be a sign you need to reduce the behavior, but otherwise ejaculation in itself is not necessarily harmful.
CLARIFICATION: The above is simply about the act of ejaculation, NOT pornography consumption. While related, that is an entirely more complicated topic.