[maket]

I'm guessing from other comments that it checks logins on a wide variety of sites, some of which may be NSFW. Some employers might not like you accessing NSFW sites.

[frederikvs]

correct, among others it checks youporn. For this check it needs send a request to that domain, which may get flagged in certain corporate IT systems.

[jacquesm]

That would be a pretty crappy check then. After all any webpage could embed that favicon.

[ghurtado]

Any page could also embed anything else NSFW, such as actual porn videos. The assumption is that these sites are generally NSFW by association.

What would you propose instead?

[jacquesm]

If a filter is set up to not just block access to but also flag based on something as trivial to embed as a URL one would hope the technology would be a little bit more involved than a single hit on a .ico file for a flag.

[ghurtado]

A web filter / proxy does not have any way to tell whether any individual HTTP request was requested as a result of HTML embedding, bookmarking, user entry or clicking on a link.

[jacquesm]

Exactly. So it shouldn't be used to 'flag' any employees.