Straight-forward regressions:
[ ] Bug 414576 - Zoom failure in 4.2.8 but not in 4.2.7 - https://bugs.kde.org/show_bug.cgi?id=414576
[ X] Bug 414818 - Krita crashes when loading files containing colorize mask - https://bugs.kde.org/show_bug.cgi?id=414818
[ ] Bug 414672 - Crash in uninitialized transform tool - https://bugs.kde.org/show_bug.cgi?id=414672
[ ] Bug 415625 - Crash in transform tool [different than the previous one] - https://bugs.kde.org/show_bug.cgi?id=415625
[ ] Bug 415932 - Some brushes doesn't follow their exact outlines as I draw with them - https://bugs.kde.org/show_bug.cgi?id=415932
[ ] Bug 415891 - Project file loads perfectly fine in seconds in 4.1.7 [and 4.2.7], never finishes loading in 4.2.8 - https://bugs.kde.org/show_bug.cgi?id=415891
More problematic...:
[ ] Bug 415086 - A file won't "draw - **very important but no idea how to reproduce** - https://bugs.kde.org/show_bug.cgi?id=415086
[ ] Bug 415773 - Krita 4.2.8 freezes when SHIFT-resizing brush [not confirmed yet but I did get some resports like this on reddit I think...] - https://bugs.kde.org/show_bug.cgi?id=415773
[ ] Bug 415213 - Transform Tool Crashing Program After resizing - https://bugs.kde.org/show_bug.cgi?id=415213
this one can be either bug 415635 or something else, but hard to determine; needs to be checked after fixing that bug to see if it works for them or not.