Squirt's Blouse is a Unique Chest Armor in Diablo IV Season 15 for All classes. It comes from Season 15 Legacy Unique; Legacy Unique: general Unique pool (permanent); Horadric Cube: Item Transmutation - Upgrade to Unique from a Common base of the same type.
Unique power
While not taking Damage, you take up to 50% more damage and deal up to [35 - 50]%[x] more damage. This bonus is reset upon losing Life.
Affixes
+Primary Core Stat ([100 - 121])
+Life on Kill ([263 - 300])
% Resource Cost Reduction ([6.0 - 7.0]%)
+% Gold Drop Rate (guaranteed affix) ([50 - 100]%)
Where it drops
Season 15 Legacy Unique
Legacy Unique: general Unique pool (permanent)
Horadric Cube: Item Transmutation - Upgrade to Unique from a Common base of the same type
All Unique items can drop at level 1 in any Difficulty since 3.2.1 (official patch notes)
General Unique loot pool / world drop - not attached to any boss loot table (one guide, another guide and a third guide)
Nightmare Dungeons, Helltide Chests, World Bosses, Kurast Undercity, Purveyor of Curiosities (Murmuring Obols) (one guide)
Uber/Lair boss ladders and Tormented bosses, Helltide chests, Whisper caches (one guide and another guide - low authority, unverified)
random drop - not listed on any Lair Boss loot table in the community loot-table cheat sheet this dataset uses; no official Blizzard list confirms it