As Ronald notes, as of 3.9.1, we are for the immediate future providing two macOS installer variants: the traditional 10.9+ Intel-64 variant that is built on 10.9 and includes Tk 8.6.8 and the new "experimental" 10.9+ "universal2" (Apple Silicon and Intel-64) variant built on macOS 11 which included Tk 8.6.10. As the new universal2 variant gains more exposure over the next releases of 3.9.x, we hope to migrate to that being the recommended variant and start to deprecate the traditional 10.9 variant for 3.9.x.  For 3.10 pre-releases, we are now only providing the "universal2" variant; the next alpha release. 3.10.0a4, should be available very shortly and its macOS installer is built with the just released Tk 8.6.11. I have only run some preliminary tests at the moment and there do seem to be some changes and possible regressions in our tests when using 8.6.11 instead of 8.6.10 but I will investigate further over the next day or so and open issues as needed. Feel free to download 3.10.0a4 and test away!

I did not see any issues with missing icons; with a Python framework build, Python and IDLE both run under app bundles with supplied icons amd that still seems to be working. Things may well be different for non-framework builds but they were before, too.