Feathers of Fatigue stacks neatly with the other bars on the right: food, air bubbles, thirst.

Thirst Was Taken, Cold Sweat and AppleSkin	Tough As Nails, Serene Seasons and AppleSkin
Underwater in iron armor: feathers above the air bubbles	Jade shows the stamina of a mount

These mods work out of the box. Each one has its own switch in FeathersOfFatigue-Compat.toml:

Mod	What it does with feathers
Droplets of Thirst	Thirst slows recovery, and being well quenched speeds it up. Regeneration can cost thirst
Serene Seasons	Winter outdoors is cold, and the summer sun is hot
Curios	The Feather Ring goes in a ring slot
Jade	Shows the stamina of a mount when you look at it
AppleSkin, Overflowing Bars	Sit nicely next to the feathers

Older Minecraft versions also support these:

Mod	What it does with feathers
Tough As Nails (26.2 and older)	Its temperature decides cold and heat. Its thirst slows or speeds up recovery
Cold Sweat (1.21.1 and older)	Your body temperature decides when you are cold or overheating
Legendary Survival Overhaul (1.21.1 and older, not 1.19.2)	The same as Tough As Nails, from its temperature and hydration
Thirst Was Taken (1.21.1 and older)	The same as Droplets of Thirst, for worlds still on the original mod (Droplets of Thirst is its maintained continuation)

These mods have no build for the newer versions. Minecraft Versions lists what each version supports and was tested with.

Feathers of Fatigue calls these mods directly. For this reason it accepts the versions it was tested with, up to the next major version. With a version outside that range, the game stops at load and names the mod and the range, so it does not crash later in the middle of play.

Mod	Accepted versions (26.3)
Droplets of Thirst	26.3-1.0.0-beta.1 up to 26.3-2
Serene Seasons	26.1.2.0.7 up to 26.1.3 (its builds for 26.x keep 26.1 numbers)
Curios	17.0.0-beta.2 up to 18
Jade	26.3.1 up to 26.4
Overflowing Bars	26.3.0 up to 26.4

Droplets of Thirst has the same rule on every Minecraft version: from <minecraft>-1.0.0 up to <minecraft>-2, where <minecraft> is the version that Feathers of Fatigue is made for. On 1.21.1, that is 1.21.1-1.0.0 up to 1.21.1-2. On 26.3, where Droplets of Thirst is a beta too, it starts at 26.3-1.0.0-beta.1.