In my view the outer appearance can be misleading especially in case of the 555 which has been produced for nearly 50 years by many companies.
For example this one looks very strange to me:
But the die is nearly the same as in this one which looks also unusual but not really fake:
In fact the history speaks for an original:
The lower is a older Sescosem which changed to Thomson (the upper one). Inside are the same dies but slightly revised.
You can´t be 100% sure but thats convincing for me.
Also this one looks kind of strange:
But the die seems to be the right one:
Let´s discuss what a (555-)fake is:
1. There is no die or a completely different die
You will find out very quickly.
2. It was some old 555 which was relabeled to make it look new or more expensive (special company)
If the original die has a marking or a structure which is known you can recognize the fake.
But especially with newer or "no-name" products you can´t be sure whether it´s a relabeled fake or they have bought the design.
With every 555-die you see your success rate in recognizing relabeled fakes gets higher as you know a lot designs and see different kind of for example a TI NE555.
3. A new 555-design is labeled with a "famous" 555-name
I´m not sure whether that´s a good business model anyway. You have to design a new chip which you can sell only very cheap.
Such "die-fakes" are a good opportunity to earn some money if you can put a cheap existing die (for example a medium power NPN) in a more costly package (2N3055 or some newer design).
I found this strange TI-NE555-dies which I posted further up and were also posted by zeptobars. They could fit in catogery 3 but I´m not sure.
See also:
https://www.richis-lab.de/555_10.htmThe marking is sometimes very strange but wouldn´t it be possible that TI has a chinese company building the last few cheap NE555-DIP and they are no longer interested in the perfect quality? The dies of "these modern" TI-NE555 seem to be all the same. There was only one die shrink. Could be a chinese fake-company. Could be a cheap TI-outsourcing...