Gamma or brightness change after each run

Hi!

I’m making a simple psychophysics experiment. The problem is that the screen changes overall gamma (or brightness) after each run making it impossible to find a threshold across runs. I found this other thread where the gamma or luminance decreased after each run but for me, it both decreases and increases randomly between runs.

I include this minimal working example with a slider to select the opacity of a graded annulus. Sometimes i barely see it at 0.03 and sometimes it is completely visible at 0.03 and the threshold is rather somewhere around 0.01 which is a huge difference.

Is there something wrong with my code (how colors or the window is defined)? Or is it some other problem?
I get this error when running the file:

\path_blabla\anaconda3\envs\psychopy\lib\site-packages\pyglet\image\codecs\wic.py:289: UserWarning: [WinError -2147417850] Cannot change thread mode after it is set warnings.warn(str(err))

I used anaconda to install psychopy according to the instructions on the psychopy website.
psychopy version: 2021.2.3

from psychopy import visual
import numpy as np

# Change these (exit program by selecting the maximum value on the slider.)
resolution = [1920, 1080]
hz = 144 # screen refresh rate
conds = [-45, 45]

def make_objects():
    win = visual.Window(allowGUI=False, fullscr=False, size=[1920, 1080], monitor='testMonitor', units='height', color='black')
    txt = visual.TextStim(win, color='white', height = 0.02, text = '', pos=(0,-0.4))
    myGabor = visual.GratingStim(win, tex='sin', mask='circle', sf=20, color='white',
                                size=(.1, .1), pos=(0,0))
    respGabor = visual.GratingStim(win, tex='sin', mask='circle', sf=4, color='white', size=(.03, .03), contrast=1)
    cir = visual.Circle(win, radius=.1*0.4, fillColor='black', lineColor='black')
    fix1 = visual.Circle(win, radius=.004, fillColor='white', lineColor='white', opacity=0.7) # inner circle
    fix2 = visual.Circle(win, radius=.01, fillColor=None, lineColor='white', opacity=0.7) # outer circle
    square = visual.Rect(win, width=.05, height=.05, opacity=1, fillColor='#141414') # fillColor=[-.95]*3
    photo = visual.Rect(win, width=.015, height=.015, fillColor='white', lineColor='white', opacity=1, pos=(0.88, 0.49))
    return win, txt, myGabor, cir, fix1, fix2, respGabor, square, photo

def show_slider(start=None, text='', scale=(0,1), gran=0.01):
    t = visual.TextStim(WIN, color='white', height = 0.05, text = '', pos=(-0.55,-0.4))
    slider = visual.Slider(WIN, ticks=np.linspace(*scale,11), labels=list(np.linspace(*scale,11).round(len(str(gran))-2)), pos=(0,-0.4),
                        granularity=gran, style='rating', labelHeight=0.01, startValue=start, size=(0.9,0.02), opacity=0.1)
    slider.draw()
    t.text = text
    t.draw()
    WIN.flip()

    while True:
        response = slider.getMouseResponses()
        if response != None:
            break
    WIN.flip()
    return response


def gabor(ori, opacity):
    assert type(opacity) == float
    GABOR.ori = ori
    GABOR.opacity = opacity
    for _ in range(np.random.choice([int(hz * i) for i in [1.0, 1.1, 1.2]])): # jittered blank
        FIX1.draw()
        FIX2.draw()
        WIN.flip()
    for _ in range(int(hz*0.05)): # gabor
        PHOTO.draw()
        GABOR.draw()
        CIR.draw()
        FIX1.draw()
        FIX2.draw()
        WIN.flip()
    for _ in range(np.random.choice([int(hz * i) for i in [0.6, 0.7, 0.8]])): # jittered blank
        FIX1.draw()
        FIX2.draw()
        WIN.flip()


def practice(slidermax=1):
    response = None
    WIN.setMouseVisible(True)
    while response != slidermax:
        response = show_slider(response, response, (0,slidermax),0.001)
        WIN.setMouseVisible(False)
        gabor(np.random.choice(conds, 1)[0], response)
        WIN.setMouseVisible(True)
    WIN.setMouseVisible(False)

WIN, TXT, GABOR, CIR, FIX1, FIX2, RESPG, SQUARE, PHOTO = make_objects()
practice(0.1)
WIN.close()

The solution was to update drivers for the graphics card.