The prettiest benchy I’ve seen... until
My money's on your part having come loose from the print bed near the end.
Proper cleaning and handling practices are a must:
(especially point 6 works wonders for many)
Yes, both the bench and the skirt were loose and in different parts of the bed.
And subsequent test prints the first layers aren't sticking at all really, even though I am wiping down with IPA each time.
I will try Dawn before the next one.
Then tell us more. Did it came loose? What filament did you use? Is the printer also in an "out of the box" state or did you do a modification (other nozzle for example)?
I had what look like the same issue with one of my first Benchys.
For me it was the issue that my z-layer was to high and that it did not stick to the sheet. First picture is the on the failed, second it work really well
I actually lowered the Z a small bit more since then.
See my post on the topic here:
Hope it helps