It's possible the car receives (silent) data updates between software updates,
No, it's not.
The entire blob has a hash for security reasons, you can't change "part" of it.
Green covered that too fairly recently-
Greentheonly said:
they must update entire firmware at least on the autopilot. Can't change a single file - breaks dm-verity. Can't overlay and have it survive a reboot (no dev overlay hooks in prod firmwares)
The only time behavior could change without an explicit firmware update from Tesla that you know about and approve to install (and that changes the listed version) is if they push a map update (which you can also see in versioning).
Updated maps can change behavior because of better info in the maps (ie corrected speed limits, or type of road, or lane data, etc), not because your car "learned" anything.
That said- there's a myriad of reasons "how the car handled X" can change WITHOUT ANY CHANGE to the software.
For example the amount/direction of light can change how confident the system is in what it sees.
So can the amount of other vehicles.
Or the weather.
Or the angle of approach to something.
Or how dirty a camera might've been.
Or your speed (we saw a GREAT example of this when a guy posted video claiming FSD beta had "learned" how to handle a U-turn, but when you actually look closely you notice the "failures" were like 15-20 mph higher approach speed than the later "success".)
Or a slew of other environmental differences.
Humans will often not notice (or care) about minor differences in conditions and just assume OMG MY CAR LEARNED!
No. It didn't.