But when examined together, a handful of recent decisions by the US Army may show that its marksmanship misses the target (pardon the pun). The Army has been seeking to replace the M-16 and M-4 rifles, examining possibilities with a 6-7mm round, which could promise improved accuracy. A new qualifications course for marksmanship debuted in Fall 2019. The standards for "marksman" and "sharpshooter" badges were also increased. "Marksman" requires 28 hits rather than 23, while "sharpshooter" requires 32 hits rather than 30. As early as 2016, you can find headlines that point to the idea that the Army's shooting may not be up to snuff.
It should also be noted that improving "Soldier Lethality" is also one of the Army's six current modernization priorities. That includes a focus on training and technology, but shooting skill could broadly be considered under that umbrella.
The Army is unlikely to state plainly that its soldiers have forgotten how to shoot. But these are the kind of steps you'd take if you felt your soldiers weren't effective shots.
It may be the case that the Army has spent years focused on deployments and less on training. Soldiers serving overseas have to know how to shoot, but may have less time to practice on the fundamentals. Similarly, athletes can improve by playing in games, but may improve more through structured training and practice.
Regardless, the Army didn't forget how to shoot overnight. It was likely a slow decay as knowledge and teaching ability left the force and attention was directed elsewhere. To start shooting straight again, it will take time and focused effort.