I recently ran into some freezes with the version 126.96.36.1991 of Affinity Designer on Windows 10 when using the Color Picker Tool. I haven't tested this with previous versions.
Most but not every time I use the color picker tool while some objects selected (doesn't seem to matter which size or number) my whole computer freezes.
After a while it's possible to use use the mouse again and switch to other programs. Clicking into Affinity will lead to another temporary freeze, eventually leading to a windows alert about the software not responding.
Watching the Taskmanager shows that Affinity keeps using an continuously increasing amount of memory and disc capacity...seems to be some kind of memory leak there.
If Affinity Designer is closed with the Taskmanager the system goes back to normal after a few minutes
The settings of the color picker tool don't seem to make a difference for the occurrence of the bug.
Using the color picker tool with no objects selected works fine
There's no problem on re-opening Affinity Designer and work again (with other tools)
You'll find my computers specifications in the attached image.
Maybe someone else could test if the problem is an overall issue.
Hope it helps on improving this great software.