In my 2d game, when I try to rotate my object 90 degrees, it sometimes takes the longer rotation ins

[still sparrow]

extends CharacterBody2D

const FLOAT_EPSILON = 0.001

@onready var shape = $CollisionShape2D
@onready var ray: RayCast2D = $Ray
var settled = false
var rotating = false
var current = 0.0
var touched_ground_again = false

static func compare_floats(a, b, epsilon = FLOAT_EPSILON):
    var diff =  abs(a - b)
    return diff <= epsilon

func raycast(origin, target):
    var space_state = get_world_2d().direct_space_state
    var query = PhysicsRayQueryParameters2D.create(origin, target)
    return space_state.intersect_ray(query)

func _physics_process(delta):
    if !settled && ray.get_collider():
        settled = true
    if ray.get_collider():
        touched_ground_again = true
    if !settled:
        return
    if !ray.get_collider() && touched_ground_again:
        rotating = true
    if rotating:
        var target = lerp(rotation_degrees, current + 90, 0.3)
        if compare_floats(rotation_degrees, current + 90.0):
            touched_ground_again = false
            current += 90.0
            rotating = false
        return
    velocity = transform.x * 80
    
    move_and_slide()

I know the code is terrible, i'm mostly messing around

[onyx pawn]

What you want is a Quaternion Slerp

That will lerp between any two arbitrary rotations, taking the route with the less rotational distance between them

What you're doing is called Euler Angle Lerping, which basically lerps between two arbitrary degrees of rotation

[still sparrow]

        var quat = Quaternion.from_euler(Vector3(0, 0, rotation_degrees))
        var target = Quaternion.from_euler(Vector3(0, 0, current + 90))
        rotation_degrees = quat.slerp(target, 0.1).get_euler().z

I tried your approach, to mixed results
This results in only a 2 degree rotation, shouldn't it be 90 degrees ?