Hi @tomášh66049311,
Thank you for reporting this issue. What version of After Effects are you currently using? The most recent version (25.2) has some changes related to HDR footage and color management that may be involved with what you're seeing.
What color space is your AE project currently using? And what are your system specs (GPU, RAM, etc)? And is your monitor able to display video in HDR?
Thank you for any additional information,
- John, After Effects Engineering Team