What I expected to happen:
Giving a player an effect and enabling hideParticles, no particles should show up.

What actually happened:
Instead of the normal particles, blue particles appear.

Steps to reproduce the issue:

• Enter e.g. "/effect @p minecraft:strength 5 1" in the chat to see that effect's regular particles
• Enter e.g. "/effect @p minecraft:strength 5 1 true" in the chat. Instead of not seeing the particles, blue ones appear.