TF1 reception issue

Thank you for trying to help me, but I think it comes from the decoder that has been installed since the digital TV was set up, because the other two TVs don't have this problem, unless it's the 4G installation.
Have a good evening.

Good evening,
TV aerial

Good evening,
What is your reception method?
Individual antenna?
Collective distribution?
TV via ADSL?

--
I call a cat a cat *
     *in French in the text

You need to check all your connections, and if necessary, redo the coaxial connectors by scraping the copper core if it is oxidized. Be careful, the slightest "hair" from the braid touching the copper core can cause interference. Make sure the connectors are up to the new standard 9.52mm (often blue) and not the old 9mm (often green) that "float" in the female connector.

--
I call a spade a spade *
*in French in the text

Thank you, but it's a bit complicated!
I'm giving up.