Proper way to declare; "examples are ficticious for data protection"

It is common to use words like "fictitious", "fake data", and even a footnote explicitly saying "these are not actual values" or "values for illustrative purposes only". It is even more common to just pick values intentionally that are obviously fake, so that no reasonable person will think they might be real, such as "John Smith|Gotham|01:11|1999|Jan|Accounting|12345" - etc.

I will however note that there is a way to handle this specific case that is even more high-level, which is just not to do this at all, because most stakeholders couldn't care less, much less even know what a float vector is or how they are suppose to interpret it. Telling people details they don't need makes many people think it must be important so they try to latch on to any random interpretation they can think of - because why are you even telling them if it doesn't matter? So if they are not a very specific type of user, just leave this out entirely.

If they are in the tiny, tiny minority of stakeholders that care about this incredibly low-level amount of detail, then it is reasonable to assume they will recognize obviously fictitious data even if you don't say it, and if you really are worried you can just give an asterisk and say its fictitious - but that's already excessive. If you need to demonstrate for some sort of officious bureaucratic sect, declare in the footnote that the data is fictitious for illustrative purposes, persuant GDPR section blah subsection blah blah blah. Give the lawyers something to smile about, if that's your audience, but you shouldn't let it take over the rest of the presentation of the work.