I have a Lenovo IdeaPad 720S with an MX150.  It was a great chip for the time when you wanted some extra umph in the GPU department but had a thin and light and didn't want to pay a lot for it.  It was great for any older game I wanted to play and allowed me to stop carrying 2 laptops (a thin and light and a gaming laptop) most of the time unless I planned on playing something current and heavy.

As time went on though, the competition, even Intel, got better and all Nvidia seemed do was keep rebadging the MX with slight improvements. It didn't take long to be unable to justify the price when integrated GPUs from AMD and Intel became just as good or better.

The go-to combo now seems to be the iGPU and maybe a low watt 3050/4050 to give something that's more playable at an affordable price.

AMD's APU's have now rendered these low end discrete cards dead and buried. Next gen Sarlak APU's from AMD will probably hit 6700XT desktop performance levels and even render 3060 mobile class cards obsolete.

According to my observation MX cards were always made from the remains of GTX cards.

Then Nvidia implemented raytracing, and had 2 concurrent production lines: GTX and RTX cards. As long as GTX cards were produced, MX cards also existed.

Now that RTX cards have been fully established, GTX card production was stopped completely. No GTX cards means no MX cards.

The lowest RTX card now takes the place of the former MX card, which is the RTX 4050.