U-Boot should ensure dtb usage is 8 byte aligned as much as feasible
The device tree specification requires that a device tree start at an 8 byte aligned memory address. Today, in some places we only ensure at a minimum 4 bytes of alignment and often this is OK. When passing on to the OS we do (with some unfortunate exceptions) ensure full proper alignment.
In at least some corner cases (certain PowerPC platform/image formats) 4 byte rather than 8 byte alignment is functionally required and so must not be broken.
One patch that started this work, but did not complete it (and did not cover all cases) is: https://lore.kernel.org/all/20221215115825.827111-1-eugen.hristev@microchip.com/ and this thread also has other feedback to the approach that must be incorporated.