Add notice about pre-1.4.2 tag with Java 8 to README

README.md

@@ -94,6 +94,10 @@ If the build fails with `fuse: mount failed: Permission denied`, you may need to
 
 ## Historical Changes
 
+* Before version `1.4.2`, Briar was build using Java 8. Newer release are built with Java 11
+  which produces different byte code breaking reproducibility
+  An [old version of briar-reproducer](https://code.briarproject.org/briar/briar-reproducer/tags/pre-1.4.2)
+  can be used to verify these releases.
 * Before version `1.1.7`, Briar needed a deterministic files system
   to work around an [Android build system bug](https://issuetracker.google.com/issues/110237303)
   which broke reproducibility.