Half-breed, still living despite WotC racism
This is PF2E, so no SRD. This is the critter the OPs group faced:Obviously, I can't speak to the stats the DM had behind the screen, but the SRD
Amorphous blobs of yammering mouths and oozing, fleshy sludge, gibbering mouthers are among the strangest creatures found either aboveground or below. Perpetually ravenous, these aberrations are always seeking their next meals, ever eating but never sated. With a nominal intelligence, gibbering...
Here's the confusion ability in PF2E terms:
Gibbering (auditory, aura, emotion, enchantment, incapacitation, mental, occult) Each creature that begins its turn within 60 feet of a gibbering mouther must attempt a DC 19 Will save. On a failure, they are confused for 1 round. On a success, they are temporarily immune for 1 minute.
A level 3 champion, ranger, and rogue with a +0 Wisdom has a +7 roll on that save as they are Expert in Will saves. So these classes actually had good odds. However none of them are classes where you'd likely put ability points into Wisdom. A cleric with a likely +4 Wisdom would have a +11 Will save as Clerics are also expert in Will.
Alchemist is only Trained in Will saves. Not sure if anyone else has this unlucky fate, but if we look at an alchemist with a +0 Wis, then at level 3 that poor sod has a +5 on that save - the worst possible situation in the game RAW unless you use the 'pre-errata' version of ability score generation, in which case you might be able to find an ancestry with a minus to Wisdom, and get that save to be as low as +4.
So that DC 19 is rough, but it's not asking you roll a 19+, it's asking you to roll a 12+ with a Champion that has no wisdom.