When I replaced the AudioQuest with a ‘regular’ HDMI cable everything worked as I want. The AudioQuest cable is from the Pearl range; it’s only short, 0.6m and was purchased in 2021.
The Arcam is an AVR390 which has HDMI 2.0a connectors and a reputation of having handshaking issues. I haven’t enabled CEC, that again is reported as causing all sorts of issues.
The Arcam is connected to a Sony 55XD8005 TV again by a regular HDMI cable.
Hope this answers all the questions.