The change at 150 could be related to Dunbar's number.

https://en.m.wikipedia.org/wiki/Dunbar%27s_number

Here's my rough understanding, from experience anyway:

50 is the level at which systems and processes start to become critical - you can't just succeed accidentally through heroism, you have to deliberately set out to learn from and solve problems or you're sunk.

100 is the level at which people can no longer self-organize and need explicit constructs to manage organization. I.e. not just 'a pool of engineers who work on the product', but a X team and a Y team and a Z team.

150 is the level at which every person can no longer know everyone on a personal level at the company. You'll need some way to handle cooperation and communication that's not "Talk to Bob", and all hands meetings can only happen at best yearly.

500+ is the point at which things will generally become stabilized / ossified enough that the ongoing structure of the company either works or it doesn't and the difficulty of changing those things becomes exponentially higher. Reorganization is a significant misnomer.

I think the difference between 100 and 150 is that at 100 people, as long as the organizational structure is right, you can still play fast and loose with corporate culture. While it'll be a stretch, each person may be able to know every other person if not by name then at least by face and role. In other words, each person's "observable universe" inside the company is the whole company.

At 150, no one can stay aware of everyone else. Your "observable universe" becomes a strict subset of the company, no matter who you are. There's no longer one company, but rather 150 different companies as seen by every employee. Direction must be constantly supplied from the top to apply corrective measures to all those different visions of the company.