For Mc...: Invisible Players Detector Resource Pack

: Replaces potion particles with a red "caution" mark and can add a "Steve marker" indicator above players' heads for exact positioning. Non-Pack Detection Methods

: Uses core shaders to uniquely change only invisibility particles to a bright yellow color without affecting other potion effects. INVISIBLE PLAYERS DETECTOR RESOURCE PACK FOR MC...

: A lightweight pack that replaces subtle particles with bold, high-contrast warnings designed for fast-paced combat. : Replaces potion particles with a red "caution"

If you don't want to use a resource pack, you can use these vanilla methods: Minecraft - Invisible Player Detector (Survival friendly!) INVISIBLE PLAYERS DETECTOR RESOURCE PACK FOR MC...

: Modifies invisibility particles to be bright yellow and changes other potion effects to different colors for easy identification.