Alignment checks on heap layouts can "leak" VM implementation-dependent alignment decisions. This is discussed here:

https://mail.openjdk.java.net/pipermail/panama-dev/2021-November/015852.html

The solution is to define a "maximum" alignment for heap segments, which depends on the element size of the Java array backing the heap segment. For instance, a segment backed by a byte[] cannot produce addresses which are more aligned than 1-byte.

This definition of notional alignment gives us back predictability.