This issue is originally discovered in 1.16.5.

However,this is most likely not fixed as of 1.17.1.

The skeletons cn shoot sideway arrows.
Modded version(Invalid):MC-220676
How to reproduce:

1. /time set midnight
2. /summon skeleton
3. /effect give @e[type=skeleton] slowness 1000 255**
4. /gamemode survival @s
5. Run around the skeleton
6. (x)Skeleton shoots sideway arrows.**

Note:This post used slowness 255,which is considered unsupported and therefore this issue might be closed as invalid.