Why did Toyota officially change the oil from 7.9 quarts to 8.5

So I had a 2021 tundra a few years ago and put in 8.5 quarts per the manual and the dipstick read full and life was good

I just got a 2016 tundra (both non flex fuel 5.7) and did my first oil change the day I got it from the dealer and since I’ve always put 8.5 quarts that’s what I did but after driving it around the next day and I let it sit on the street leveled and flat went to the gym for an hour and checked the oil and it read as over filled! My friend with a 2017 tundra said his manual puts in for 7.9 so I checked mine and to my suprise it said the same

so this morning I checked it again after it sat overnight and it reads full now instead of overfill so I’m beyond confused if it took 8.5 for all these years and Toyota realized it and changed it during 2020? I included two pics one where it reads just full after sitting overnight and the other where the black line is after driving and sitting for an hour

 

My 2008 says 7.5 with filter. Maybe the 07-09 had different from 10-13. The. 14-21 had more, strange.

 

My 17 is 7.9 with filter.

 

My 2020 is around 8.25 - 8.5

 

This is from Toyota TIS. It's 7.9 without a filter. 8.5 with.



From my experience this is how the dipstick read.
6 quarts low mark
7 quarts almost in the middle
8 quarts to the full mark
After running need to add .5 to get back to full mark so capacity with oil and filter is 8.5qts

 

8 always gets me where I want to be.

 

My 2017, as already mentioned, says 7.9 US quarts. I put in 8.4 US quarts and all is at peace with the world.

 

My 2021 takes 8 qts to hit the midway point on the dipstick, 8.5 snugs me right up to the fill line

 

8 quarts gets mine to just a tiny bit below full mark. I check it hot a few minutes after running like my manual says.

 

My 2008 manual for the 5.7 says 7L (7.4 quarts) with filter (below picture). One time I just googled how much oil to put in a 5.7 and it was 8+ quarts. The dipstick showed it was overfilled. I wondered why so I checked my manual and saw it should have been 7.4 quarts. Not sure where that extra oil goes in the newer trucks.
For the dipstick, I normally have one side that reads lower and the other side reads higher. The higher side is often streaky (doesn't completely cover the width of the dipstick). I experimented once adding a little oil at a time and the lower side came up a little each time as expected while the higher streaky side jumped around.