This mirror:

http://iso.qubesosfasa4zl44o4tws22di6kepyzfeqv3tg4e3ztknltfxqrymdad.onion/

gives:

Qubes-R4.3.0-x86_64/                               19-Dec-2025 09:48                   -
Qubes-R4.2.4-x86_64.iso                            17-Feb-2025 22:11          7266004992
Qubes-R4.2.4-x86_64.iso.DIGESTS                    17-Feb-2025 22:11                1251
Qubes-R4.2.4-x86_64.iso.asc                        17-Feb-2025 22:11                 833
Qubes-R4.2.4-x86_64.torrent                        17-Feb-2025 22:11              139199
Qubes-R4.3.0-x86_64.iso                            19-Dec-2025 01:17          8176568320
Qubes-R4.3.0-x86_64.iso.DIGESTS                    19-Dec-2025 01:17                1251
Qubes-R4.3.0-x86_64.iso.asc                        19-Dec-2025 01:17                 833
Qubes-R4.3.0-x86_64.torrent                        19-Dec-2025 01:17              156518

I see no way for someone with R4.2.4 to obtain R4.3.0 by just fetching the changes. Is that correct? If we want to maintain a copy of the latest ISO, we must grab the whole ~8gb ISO file every release?

I checked a couple mirrors (not all of them), and saw no jigdo templates.