TV screen flicks to black and back again

A few times in the last hour my TV screen goes black for a moment and then returns with the HDR marker showing in the corner. The audio continues properly during this and the video and audio are still in sync.

This used to happens a few months again (but not A few times in an hour) and at the time I thought the cause was a damaged desk fan interfering with the AppleTV.

However that fan is long gone and now I’m not sure if it is the AppleTV or the LG television that showing the black screen.

can anyone suggest how I can figure the cause? Screen has flicked to black about five times while I type this.