Per the Suggestion spell, on a successful save the target "is unaffected and thinks you were talking to them normally, not casting a spell on them." Only on a critical success does the target know you tried to control it.
So what about bystanders? Suggestion has somatic and verbal components, but are they obvious to bystanders as a spell being cast (in which case a success by the target resists the compulsion but not an implied "you don't realize I'm casting a spell on you" effect) or are bystanders unaware that a spell was cast unless they see the effects on the target? The former would eliminate the usefulness of the Conceal Spell feat, but only in this very particular case, so I'm not sure which way to go on this.
Suggestion now has the Subtle trait, which means it requires no incantation, has no visible manifestations. It is not obvious. It is the same thing Conceal Spell does to spells that aren't already Subtle.
The way to go on this is stop using the pre-remastered version of Suggestion. Player Core solved this problem by getting rid of verbal and somatic components and adding the new subtle trait to Suggestion and other spells like it.
https://2e.aonprd.com/Spells.aspx?ID=1693
Suggestion now has the Subtle trait, which means it requires no incantation, has no visible manifestations. It is not obvious. It is the same thing Conceal Spell does to spells that aren't already Subtle.
This is a major improvement
Suggestion now has the Subtle trait, which means it requires no incantation, has no visible manifestations. It is not obvious. It is the same thing Conceal Spell does to spells that aren't already Subtle.
Outstanding, I hadn't switched over to the Remaster yet. This makes a lot of sense. Thanks for pointing this out!