Firmware update version 1.3.2 was released for the EOS 5D Mark IV in May 2021 – and then almost immediately removed. Version 1.3.3 incorporates the following fixes:
1. Improves the camera's connection compatibility to a PC while using a USB 3.0 or higher compatible cable.
2. Fixes an issue in which self-timer shooting cannot be performed in firmware version 1.3.1 and 1.3.2.
3. Fixes an issue in which an electronic beep does not sound when registering an AF frame as the AF start position in firmware version 1.3.1 and 1.3.2.
4. Fixes an issue, in which a small sound is generated from the speaker when the power is turned on in Firmware Version 1.3.2.
*Item 1 applies to Version 1.3.2, whereas Items 2 through 4 apply to Version 1.3.3
https://www.canon.co.uk/support/consumer_products/products/cameras/digital_slr/eos-5d-mark-iv.html?type=firmware