The bug
Wolves shake off water when it's raining if they are standing partially inside a non-full block. For example, this afects fence posts, doors & trapdoors, chains, lightning rod, etc.
Reproduction steps
Spawn a wolf inside an enclosure like so:
[media]
Set weather to rain using
/weather rain
Push wolf against the fence posts.
Expected & Observed Behavior:
❌ - The wolf shakes itself dry from the rain
✔ - Wolf should remain wet as there is still downfall of rain on top of the wolf
Notes
(This note is not part of the original issue, and has been added after the resolution of other very similar issues)
Linked issues
is duplicated by 2
Attachments
Comments 11

I have rewritten your report a little bit because it appears all (or most?) blocks with collision box are affected. I hope that is alright for you.
This issue closely relates to: MC-265045, MC-265046, MC-265047, MC-265048, and MC-265049, which have all been marked as "Won't Fix".
Specifically, the displayed beahvior here and in the previously listed issues all stem from the same source in the code, and would all require the same fix. (See code analysis in MC-265045 for the source of the issue)