The underlying causes of these changes are Germany (1) continuing to spend less than 2% of GDP on defense; (2) its 2019 announcement that its pushing back its 2% target date from 2024 (agreed upon in 2015) to 2031; and, (3) continued German support for Nord Stream 2.
America is publicly penalizing Germany for the above reasons, which will likely disincentivize similar actions by nations receiving US troops from Germany and other host nations in Europe. Moreover, it seems some troops are likely slated for rebasing in the Indo-Pacific which will bolster US' power there.