I also just checked a handful of processes I have access to, and at least in these cases, the fin width doesn't scale with the technology name (e.g. 5nm and 7nm has 8nm fin width drawn in layout, and model indicates 27nm "width" per fin). This isn't much of a surprise to me, because foundries are just decreasing the number with newer generations of the tech, even if the lithography (the method by which features are etched into the silicon) hasn't significantly changed. For example, 3 generations of a single process were called 7***, then 5***, then 4***.
That's your bias. To a process engineer the parameter that matters is what wavelength you are blasting the mask with and what size a feature it can create.
These processes are not exactly standardised either it would be a major undertaking to take an architecture from TSMC 7nm to 5nm let alone moving from TSMC to Samsung, Global Foundaries or if at all possible Intel.
Not unlike how there are pipeline phases that are just a little longer than they theoretically could be (because all of their neighbors have to line up with each other). If you can fix the bottleneck then everything else can shine, causing a magical, outsized improvement.
In fact, the node number has never referred to transistor dimension, but the length of the gate electrode. A transistor would typically be about 4 times larger than that.
The reason to refer to the length of the gate electrode is because that was always the smallest feature printed on the chip. And that is what defined the required resolution of the lithography process.
So, a lithography process with a resolution of 32nm would be able to print chips with 32nm gate lengths.
Much has changed, and now transistors are no longer planar, they are 3-dimensional fin structures (FinFETs). The gate length scaling has slowed down, and now is not the smallest feature on the chip anymore.
The smallest feature in a modern FinFET process is actually the with of those 'fi s' that form the transistor channels.
And as if by magic, they correspond pretty well to the node names, i.e. a 5nm process will have a fin width of about 5nm.
You will likely not find that mentioned anywhere, it's just a fun fact that I noticed as a VLSI technologist.