I was looking at how circles and sliders interacted together in 2B mapping when I thought it would be useful to take a look at autofail. So, I used a map with those settings:
BPM=164
CS=3
AR=4
OD=0
HP=6
Slider tick rate=1
and that only included those 3 patterns with no repetition:

-4 circles stacked on the same beat


-2 sliders that start on the same beat


-1 slider with circles placed every beat of its duration except the first where there is only the sliderhead (it's what I wanted to use for autofail testing)


This slider lasts 20 + 3/4 beats which is about 7.6 seconds and disappears in the editor as soon as the 3rd beat is not visible in the timeline anymore:

3rd beat is visible top left


1/16th of a beat later, it is not anymore and the slider disappeared

(Note: I increased the slider tick rate to 4 for precision but I had to delete the second pattern because it hit the HP bar into the ground lol.)
During gameplay, according to this pishifat video https://youtu.be/8teIBNQfr7Q, the slider should trigger autofail and make the ball show that I am clicking it even if I don't after 1.320 seconds which is (considering the slider starts at 00:14:155) at 00:15:475, so the slider ball would be here:


However, upon testing, I didn't autofail. The slider simply stopped working a small amount of time after 00:15:475 (only one tick disappeared after the ball reached this mark) and didn't reward a 300; a 100 or a 50 on the sliderend but it would still keep track of whether or not I was clicking and I got the score in local:






It appears that autofail is gone but however, it looks like what caused autofail before now prevents the upload of the score: after playtesting my map and the top diff of this set that was taken as an example in the video (beatmapsets/598905#osu/1265925), I got in the bottom right corner a message that says "An error has occured during the computation of the score":




I really thought autofail was gone ;-;