Instant Damage and Instant Health from non-command sources cannot be detected

A creature receiving Instant Damage and Instant Health from a source other than a command cannot be detected through NBT checks or predicate checks.

For example:

Use a repeating command block to execute this command:

execute as @e[nbt={active_effects:[{id:"minecraft:instant_damage"}]}] run say magic damage

If the player drinks a potion of instant damage at this time, the player will not say "magic damage".