Yes, I did found a solution.
I consider it as a workaround but I’ll mark this thread as resolved.
I setup a cron job (crontab -e) on the raspberry pi which is running the magic mirror:
*/30 6-22 * * * tvservice --preferred 35 22 * * * tvservice --off 55 5 * * * tvservice --preferred
From 6 am til 10:30 pm it powers on the HDMI port with preferred settings. At 10:35 pm the HDMI display is switched off and switched on at 5:55 am.
It avoids the issue described above but it is not the solution I had in mind at the beginning.
I also ordered a banana pi M3 which is more powerfull (ARM cortex A7). Hopefully it will finally solve this issue.
How is the result with your Banana Pi? Did you try it yet?
I have the same problem with flicking after it reaches 65 degrees C. I’m also wondering if you have any cooling attached to you Pi?