The bug
Squids choose the direction they are simming in randomly. This means that they sometimes also try to swim "through" a wall. Whereas other mobs trying to walk against a solid wall just collide with it, squids sometimes glitch into it (maybe client-side only).
The reason
The following is based on a decompiled version of Minecraft 1.10 using MCP 9.30.
The reason might be that the class EntitySquid is overriding the method net.minecraft.entity.EntityLivingBase.moveEntityWithHeading(float, float).
Linked issues
is duplicated by
relates to
Attachments
Comments
migrated
JUE13
Confirmed for 17w17b & 17w18a
migrated
Confirmed for 1.13.1.
j_p_smith
Confirmed in 1.15.2 and 20w21a.
migrated
confirmed in 1.16 pre-release 5
Spacebar
Confirmed for 1.16.4 pre-1
migrated
Affects 1.16.4.
Avoma
Can confirm in 20w46a.
Avoma
Can confirm in 21w03a. Also affects glow squids.
Avoma
Can confirm in 21w05a.
Avoma
Can confirm in 21w05b.
Avoma
Can confirm in 21w06a.
Orbic
In 21w11a
Orbic
In 21w13a
Orbic
21w14a
Orbic
Confirmed for 21w15a
Orbic
Affects 21w17a
Orbic
In 21w18a
Orbic
Can confirm for 1.17
ampolive
Can confirm in 1.17.1.
ampolive
Can confirm in 21w37a.
Orbic
Still in 1.18 Pre-1
Orbic
Affects 22w05a
AMGAMES04
Can confirm in 23w14a
migrated
Related to MC-208015
Spacebar
Affects 1.21.1
[Mod]Les3awe
Fixed in 24w33a.
Can confirm for 1.11. Probably client-side only as you say.