finding data about underreporting of sexual harassment in the workplace is by definition difficult, since it is by definition not being reported, so anecdotes are all we have in many cases.
In this case, the data is moot. It doesn't matter if 10% of women experience this, or 90%. Whether or not it is a problem is not in debate. It is a problem. Preventing sexual harassment is everyone's responsibility, even if you are not the one harassing.
Of course the scale of the problem makes a difference. People are also being murdered on a daily basis, but we don't claim it affects the labor force at scale (like "there is a shortage of women in STEM because they have all been murdered"). Just like murders should be prevented, sexual harassment should be prevented. But that doesn't necessarily make it a large scale problem.
As for the linked problem, I criticize that it doesn't properly define sexual harassment. The comparison here is to a guy who proposed sex on a first work day and threatened a stunted career. Is that really what women experience all the time. Or is it mostly that an unwanted colleague is attracted to them? The methodology is also not clear (very likely they only asked women, which seems rather one-sided. For "real" crime there is a reason for there being courts and judges).
If you want a source though, here is one: (https://hbr.org/2016/10/why-we-fail-to-report-sexual-harassm...)
In this case, the data is moot. It doesn't matter if 10% of women experience this, or 90%. Whether or not it is a problem is not in debate. It is a problem. Preventing sexual harassment is everyone's responsibility, even if you are not the one harassing.