Drop shadow results are unusual when converted to grayscale
Version: 23.1 and 24.2.3
1. Create an object
2. use drop shadow from appearance menu
3. From the Edit menu, select Edit Color and then Convert to Grayscale.
After conversion, the drawing of the drop shadow is not normal.
There will be a problem even if you save it as a PDF.
Version 22.1 does not have this problem.
Confirmed here as well. I found that editing the drop shadow in the appearance panel fixes it though: change to a different blur value makes it blurry again. You can change back to the original blur value and it will retain the blur.
Alternatively I found that if you convert back to CMYK from your grayscale object you keep the gray values* and the blur gets fixed.
It's a workaround but I can see that being annoying if you do that color -> grayscale conversion alot.
*value for the K channel matches the tint value from the grayscale version, but has empty/zero-value CMY channels which may not be desirable.