Does the effect of Hypnotic Pattern persist after concentration is lost?

Question

I have a question about the spell hypnotic pattern: if nobody attacks or shakes the creature, the creature stays in that condition for the duration even if the concentration is lost?

The spell is clear stating that the spell ends for the affected creatures when they get any damage or someone shakes them, but it never says "or when concentration is stopped"

So I was thinking: It is possible that the duration of the spell of 1 minute means that the spell remains in the area working that entire time? I mean, if another creatures enters the area then it has to make a save in order to avoid the charm.

If the concentration is lost then the spell ends for the area but the affected creatures stay incapacitated (because for them the only way the spells ends is being damaged or shaked)

I want you people to let me know why this approach could be wrong because that's another way to understand this spell

Or is this a DM interpretation?

Answer 1

The effect ends when concentration ends.

Hypnotic pattern states:

On a failed save, the creature becomes charmed for the duration.

The spell’s duration is:

Concentration, up to 1 minute

When concentration ends, the duration ends, and when the duration ends, the effect ends, since the creature is only charmed “for the duration”.

A creature is only affected if they are in the spell’s area when the spell is cast.

In your question, you also ask:

if another creatures enters the area then it has to make a save in order to avoid the charm?

No, this is not the case. Hypnotic pattern states:

The pattern appears for a moment and vanishes. Each creature in the area who sees the pattern must make a Wisdom saving throw.

The pattern is only there for a brief moment, and you are only affected if you see it. There is no pattern to see if you enter the spell’s area on a later turn.

Answer 2

Duration ends early when concentration is lost

A spell effect ends when concentration is lost. The line:

Concentration, up to 1 minute

means up to one minute as it says but it also means only as long as concentration is maintained.

The rules for concentration state:

If you lose concentration, such a spell ends.

The meaning of the spell ends is identical with its duration is over. You can both say

the spell ends because the duration is over

(which you noted) but also:

the duration is over because the spell had ended

which is relevant for your case.

TL;DR: the condition ends when concentration is lost.