In fact this is a weird strategy all the newspapers around the globe have started doing in the past few years, and this is why Google has been started switching a lot of the requirements (including the nex Experience for trustworthyness)
First of all check that this is not "Forbes" but "Forbes Wheels"
It's like the "automotive" section for Forbes, so that "subfolder"
https://www.forbes.com/wheels/ has 100% topic authority, BUT, they also preserve the omega big domain authorty from forbes.com (and this is why they did so).
You can understand what I'm talking about, if you check archive.org
They started this subfolder, back in 2020, like most of other newspapers.
This has been a common practice, for example, videogame magazines, have merged into big newspaper in a subfolder like
www.bignewspaper.com/videogamemagazine/
So this is a valid strategy nowadays, but as a I say, Google is trying to set their mechanisms to stop it.
In this forum we do blackhat at a little scale, and occasionally we feel bad for being so "dirty". But the huge newspapers have discovered the biggest blackhat method probably of all time with this technique, called authority stacking and it works. And the best thing is that the entry barrier, is completely beyond any blackhatter possibilities. We can't really replicate this, because it's unlikely you have a DR80+ newspaper and the money to buy a DR70+ magazine to merge with.