Samsung TV dims for a second after running electric blind - power interference?

Hello,
problem:
After switching on the roller shutter with the key switch, the TV dims for 1 second (black screen).
Tv connected to cable TV decoder with hdmi cable.
I don't know how the installation is made as it is a developer's flat. However, the sockets are close to the roller blinds, so it is highly likely that the roller blinds are powered from this circuit.
The problem arose recently - after changing the TV.
On the old one it was rather ok or I did not notice this phenomenon.
Similar topic to this [url= https://www.elektroda.pl/rtvforum/topic3511568.html] .
Unfortunately the author did not share the solution.
I have read a lot about the hdmi cable but is this really a good lead?
I am targeting a faulty connector.
What do you guys suggest to check?
Greetings

>>21527639 .

If you disconnect this set-top box from the TV (unplugging the HDMI cable) does the TV also dim when you switch on the blinds, the same when you unplug this set-top box from the mains?