I have setup ZWO ASI120MM mini with the internal Guider with KStars 3.4.1.
I have set Exp to 3 Seconds and Auto Star enabled.
When the Guding Calibration starts, the FIRST Frame takes a 9 second exposue:
2020-03-30T19:23:35: [INFO] Download complete.
2020-03-30T19:23:35: [INFO] Exposure done, downloading image...
2020-03-30T19:23:26: [INFO] Taking a 9 seconds frame...
Based on this very bright image, it can occur that its complete white or it selects a very dark star for guiding.
I have not found any possiblity to change this setting.
This was done in order to properly detect the stars. Autostart detection was having issues with 1-2 second images, so this is why. Apparently no one had issue with this for the last couple of years since it was added.