With the release today of 5.16.0 final, this major new Plasma version is now ready to move to all users. It has been been tested in the [kde-next] repo for the last 4 weeks, so no issues are expected.
Also moved the last few days were the usual monthly updates of Frameworks (5.59.0) & KDE Applications (19.04.2).
Qt 5.13 RC is currently being tested in the [kde-next] repo, final version of 5.13 should be released this week. Full rebuilds of Frameworks & Plasma have already been done for this Qt version.
Major updates for some base packages have also occurred, this includes a move to Glib2 2.60, Iptables 1.8.3. Updates to Poppler & Libindi required a good amount of rebuilds too.
With the above it is probably clear, a new ISO is needed. That will also offer the option to properly test (on an ISO also) a new stable kernel (will be 5.1xx), which is certainly needed with the major CVE found in the 5 series kernel, see the discussion https://forum.kaosx.us/d/2372-intel-hardware-severe-kernel-cve for why the stable kernel is not updated yet.
New ISO will also see big changes in the installer Calamares, currently only tested locally, but will be up soon.