The case of the ever-shrinking D score. About 10-12 years ago, the Yurchenko 1.5 was among the most common vaults in international competition. Teams (at least, perhaps outside the big four) would bring athletes to the world championships and the Olympics specifically because they had a Yurchenko 1.5 to use for the team score, and Nastia Liukin won the 2008 Olympic all-around with a Yurchenko 1.5—still probably the best one ever performed.
In present-day elite, this vault is moving toward the scrap pile. We do still see it of course (all-around qualification at the Tokyo Olympics brought us eight gymnasts performing Y1.5s), predominantly from those aiming to make the all-around final but who are mostly relying on bars and beam scores and just need something vaguely close on vault.
A major change in the pervasiveness of the 1.5 also came in 2009, when the value was dropped two tenths even though the rest of the Yurchenko layout vaults stayed the same. It stopped being more valuable to do the 1.5 than the full because the full was worth only three tenths less and was clearly easier. Now, it’s very common to see gymnasts progress straight from the full to the double and not bother with the 1.5.