I must be seeing this wrong, because it seems to me the data indicates faster expansion in the past, contrary to Adam Reiss' study that led to the birth of the notion of 'dark energy'.
In Reiss' seminal study, [https://arxiv.org/abs/astro-ph/9805201], which was followed by others [https://www.researchgate.net/publication/231060958_Measurements_of_O_and_L_from_42_High-Redshift_Supernovae] that confirmed the measurements (and earned him the 2011 Nobel), high redshift (very distant) Ia supernovae are 15-25% dimmer (i.e more distant) than the current Hubble constant (circa 74 km/s/megaparsec) would predict from their redshift. This lesser luminosity (or greater distance) in the distant region was concluded to signify the universe's expansion is accelerating, rather than slowing down as would be expected from the effect of gravity, as a ball thrown upwards by hand will rise more slowly each second until it stops rising and falls back down. Thus, that some effect must be accelerating the expansion of the universe, referred to by the placeholder name 'dark energy'.
This measurement generates a graph where low redshift (closer) supernovae seem to follow a straight line along the Hubble constant, and then in the more distant region the plot goes up from this straight line, as they are further than their redshift would predict, forming what I call for the purposes of this question a 'shallow V' shape.
[pages 267-269, How Old Is the Universe?, by David A. Weintraub, available at http://184.108.40.206/main/3FF82B0C945C31FF63E4388ED31AB7F9]
The standard answer is something along the line "The argument is pretty straightforward, and can easily be understood with a real-world example. Consider two cars leaving your house. They start out going at the same speed. But over time, one car speeds up, while the other slows down. After some time, which care will be farther away from you? The one that’s speeding up, of course. That’s obvious. And something that’s farther away looks dimmer (at least if they have the same intrinsic brightness)."
This explanation - that the universe currently expands at a faster rate than in the past - does not seem to explain the “shallow V” curve we see. It would explain a “shallow A”, with a higher Hubble constant in the present and a lower one in the past. We see a curve (or a line with a bend on it) that - it seems to me - cannot be interpreted other than the greater increment being at the point of departure, most distant from us, not nearer to where we are, ie. with a higher Hubble constant in the distant past, say around 80-90 km/s/Mp.
How can we be seeing this curve we see with the accepted interpretation? Should not the curve be bending the other way? Obviously I must be seeing this wrong, but where is my error?