[MC-167008] Slow Falling doesn't affect squids or glow squids

The slow falling effect does not slow down the movement of squids or glow squids while mid air.

Command to Reproduce

(squid)

/summon minecraft:squid ~ ~30 ~ {active_effects:[{duration:-1,amplifier:0b,id:"minecraft:slow_falling"}]}

(glow squid)

/summon minecraft:glow_squid ~ ~30 ~ {active_effects:[{duration:-1,amplifier:0b,id:"minecraft:slow_falling"}]}

Code Analysis

Code Analysis done by [Mod] Anthony Cicinelli
The issue here is that there is no check for the effect causing vertical movement to stay the same in the aiStep method

Current Code

net/minecraft/world/entity/animal/Squid.java

...
else {
         this.tentacleAngle = Mth.abs(Mth.sin(this.tentacleMovement)) * (float)Math.PI * 0.25F;
         if (!this.level.isClientSide) {
            double d1 = this.getDeltaMovement().y;
            if (this.hasEffect(MobEffects.LEVITATION)) {
               d1 = 0.05D * (double)(this.getEffect(MobEffects.LEVITATION).getAmplifier() + 1);
            }
            else if (!this.isNoGravity()) {
               d1 -= 0.08D;
            }

            this.setDeltaMovement(0.0D, d1 * (double)0.98F, 0.0D);
         }

         this.xBodyRot += (-90.0F - this.xBodyRot) * 0.02F;
      }

Fixed Code

net/minecraft/world/entity/animal/Squid.java

else {
         this.tentacleAngle = Mth.abs(Mth.sin(this.tentacleMovement)) * (float)Math.PI * 0.25F;
         if (!this.level.isClientSide) {
            double d1 = this.getDeltaMovement().y;
            if (this.hasEffect(MobEffects.LEVITATION)) {
               d1 = 0.05D * (double)(this.getEffect(MobEffects.LEVITATION).getAmplifier() + 1);
            }
            else if(this.hasEffect(MobEffects.SLOW_FALLING))
            {
               //Adding a check for slow falling and changing the speed fixes MC-167008
               d1 = -0.05D * (double) (this.getEffect(MobEffects.SLOW_FALLING).getAmplifier() + 1);
            }
            else if (!this.isNoGravity()) {
               d1 -= 0.08D;
            }

            this.setDeltaMovement(0.0D, d1 * (double)0.98F, 0.0D);
         }

         this.xBodyRot += (-90.0F - this.xBodyRot) * 0.02F;
      }