I have the Liberty Air 2 Pro for a couple of days now. When I turn on any of the ANC modes, I hear a flickering noise from the Left earbud. There is not such a noise in the right one. I did the Fit test through the app and the seal seems good. Also I can verify that the isolation when I am not using ANC is good. This flickering happen only for the left earbud and only with the ANC on. This flickering noise is louder when I am in a call rather than when I am just hearing music.
I run a couple of tests based on the comments and the suggestions.
I reset the earbuds, which also reset the Hear ID. So I used the earbuds without hear ID for a couple of days listen to music or making calls.
The flickering noise still exists on the left earbud (only on the left). A friend described that noise as a small cicada, which is accurate. It is louder than white noise. Clearly has some to do with ANC. I can hear it now almost always when hearing music, having call or just having the earbuds on my ears without listening to anything. The sound is distinctable when the volume is low or when the sound pauses or there is a pause in the conversation. So probably is something extra that ANC adds to the stream.
I used the earbuds in different locations, some where quiet and in other there was noise. I also tried all the available ANC modes. The flickering noise the same. Sometimes putting a box around my left ear or covering it with my hand (with out touching the ear or the earbud) stops the flickering. However if I remove it after a couple of seconds the flickering begins again.