66,6 Mbps = 8,325 MB/s. That's a normal download speed for my DSL connection, what is so evil about that speed?
The screenshot clearly shows 66.6 Mbps, not 66,6.
(Also, I think the EVIL comment relates to some superstition around the number 666.)
By the way, I think I once saw a picture of an elevator in a building that had a floor 50 despite only having 36 floors. (Every number with a "4" in it was missing due to some Asian languages (Chinese and Japanese at least) using the same word for 4 and "death".) Similarly, in many Castlevania games, Death has exactly 4,444 HP.
The screenshot uses a dot to indicate the decimal behind the dot as it's the normal usage apparently in the country where the website is based and I use a comma to indicate the decimal behind the dot as it's the normal usage in the country where I am based (you can even see my country below my username), so 66.6 equals 66,6 - it's the exact same number translated to a different notational system.
*edit: both uses are about as evenly spread: https://en.wikipedia.org/wiki/Decimal_separator#Hindu-Arabic_numerals
But you are right in noticing the evil probably relates to the number 666 (which I failed to notice as I just saw a speed of approximately 66).
Funny how different autistic people (I have ASD myself) notice and fail to notice different meanings in the words and numbers posted by others.