What are the differences between the various SDK builds?

[TD-er]

This was asked first at the esp8266/Arduino repository but closed there as they also have no clue and it is better asked here.

I have been switching between various versions like PIO_FRAMEWORK_ARDUINO_ESPRESSIF_SDK22x_191122 and PIO_FRAMEWORK_ARDUINO_ESPRESSIF_SDK22x_190703.

On most units the 'November' build works just fine, while on some units the 'July' build was the only one that could reliably make a stable WiFi connection.

Purely based on what I'm observing, it seems some default values may have changed.
For example:

• Timeout for WiFi scanning
• initial connection speed
• Delays between actions.

But there are way too many variables possible to even start digging into what may have been changed between these SDK builds.
So maybe someone can shed some light on what actually has been changed with respect to WiFi configuration and when to use what SDK build.
Or how to interpret these differences so we can set them on our own.

As already stated by some in the (closed) issue; the change logs and/or the commit messages are not really informative on what has changed.