I am uploading a NMU to DELAYED/10 in order to fix this.
The debdiff is attached.
diff -Nru grub-imageboot-0.6+nmu1/debian/changelog
grub-imageboot-0.6+nmu2/debian/changelog
--- grub-imageboot-0.6+nmu1/debian/changelog 2021-01-02 17:02:28.000000000
+0000
+++ grub-imageboot-0.6+nmu2/debian/changelog 2023-10-13 17:22:12.000000000
+0000
@@ -1,3 +1,10 @@
+grub-imageboot (0.6+nmu2) unstable; urgency=medium
+
+ * Non-maintainer upload
+ * Convert to source format 3.0 (Closes: #1007592)
+
+ -- Bastian Germann <b...@debian.org> Fri, 13 Oct 2023 17:22:12 +0000
+
grub-imageboot (0.6+nmu1) unstable; urgency=medium
* Non maintainer upload by the Reproducible Builds team.
diff -Nru grub-imageboot-0.6+nmu1/debian/source/format
grub-imageboot-0.6+nmu2/debian/source/format
--- grub-imageboot-0.6+nmu1/debian/source/format 2011-07-11
10:32:50.000000000 +0000
+++ grub-imageboot-0.6+nmu2/debian/source/format 2023-10-13
17:22:12.000000000 +0000
@@ -1 +1 @@
-1.0
+3.0 (native)
