Doesn't even look like a speed limit to me. Could just be advisory.
In America, a white rectangle signifies that it is a regulatory sign.
Regulatory color scheme, but that's not really a regulatory message...
It should have to be correctly formatted to be valid. Other than the number, SPEED LIMIT is not designable when it comes to adornments, omitting words, etc.
Locally, I remember asking about this sign (
https://goo.gl/maps/tGndYJt9RoXuP6uG8) over 10 years ago which was put up by the university on what may be a road owned by the university now or still owned by Akron--who knows. It's tiny, non-reflective, and nonstandard, and therefore not really enforceable. But they have doubled down with a "Your Speed" sign ahead of that which frowns if you are above 25 and flashes "slow down" if you are above 30. Still, there is no actual speed limit sign.
The missing streetlight at a busy crosswalk, which is pitch black when outside of daytime hours, ought to have been fixed but instead we have these crazy signs.
It's worth noting they
are capable of fixing inappropriate signs. This one (
https://goo.gl/maps/3sSBFF6kfpacZV6T6) had forever been "15 MPH" in red Helvetica on white until August 2019 when small but correct signs replaced it (facing both ways). They should have ordered a 25 one for the other location while they were at it.