Marker pose flickering one axis from -4 to +18 when camera is not moving

Question

I'm taking a sequence of frames from intel real sense and detecting april tags, I noticed the axis is flickering even camera is not moving. euler angle y axis is changing(visually and numerically) from -12 to +4 (bottom of image.)

import cv2

from realsense_class import realsense

import apriltag

import numpy as np

from rot_to_eul import rotation_angles

rs =realsense()
detector = apriltag.Detector(None, searchpath=apriltag._get_dll_path())

while True:

    frame = rs.frame()

    result, overlay = apriltag.detect_tags(frame,
                                               detector,
                                               camera_params=(602.46772263,601.47613486, 317.73338684, 238.16057326),
                                               tag_size=0.06,
                                               vizualization=2,
                                               verbose=0,
                                               annotation=True
                                              )

    #camera pose estimation

    if len(result) >0:
        pose = result[1]
        
        rotM = pose[:3, 0:3]
        tvec = pose[0:3,3:4]

        print("Euler_Angles",rotation_angles(rotM,'xyz'))