Canon EOS R6 Mark II Mirrorless Camera with 24-105mm f/4-7.1 Lens - Manual (Page 267)

Focus Breathing Correction
Angle of view fluctuations from changes in focal position during movie recording can be
reduced.
This feature can be configured when [
Distortion correction ] is set to [ Enable ].
Caution
Applying focus breathing correction will narrow the angle of view. The extent of
narrowing depends on shooting conditions.
Test focus breathing correction before use, because the image processing may
affect apparent image resolution and noise.
Optimal correction is applied based on the position of the focusing distance range
switch on the lens. (The correction is also applied in MF mode.) Focus breathing
correction is not applied to any difference between the actual focusing distance and
the range of the switch.
Movies with abrupt changes to the angle of view may be recorded if you move the
focusing distance range switch during recording.
Correction artifacts may occur, depending on the lens and shooting conditions.
267