Canon EOS R6 Advanced User Guide - Page 311

Caution HDR movie recording is not available with [ : IS (Image Stabilizer) mode] set to [ Digital IS], or when set to [ : Time-lapse movie], [ : Highlight tone priority], [ : Canon Log settings], or [ : HDR PQ settings]. Since multiple frames are merged to create an HDR movie, certain parts of the movie may look distorted. This is more noticeable in handheld recording affected by camera shake, so consider using a tripod. Note that even if a tripod is used for recording, afterimages or noise may become more noticeable, compared to normal playback, when the HDR movie is played back frame-by-frame or in slow motion. Image color and brightness may change significantly for a moment if you change settings for HDR movie recording. Also, the movie will not be updated for a moment, and the frame stops momentarily. Be aware of this when recording movies to external devices via HDMI. Note The recording size is (NTSC) or (PAL). 311