Hello everyone, I've been browsing this forum but I didn't find similar vertical lines like this on Panasonic Plasmas

So they are not all over the screen but there's lines on both halves of the screen. The lines are also present with no signal, at least some of them but I can't distinguish all of them with no input. With no input the vertical lines on the right side are definitely more visible.
It started with one line half a year ago, then two and has been increasing the number of lines.
Where or what could be the problem? What steps should I take? What possible fixes should I try? Thanks in advance

So they are not all over the screen but there's lines on both halves of the screen. The lines are also present with no signal, at least some of them but I can't distinguish all of them with no input. With no input the vertical lines on the right side are definitely more visible.
It started with one line half a year ago, then two and has been increasing the number of lines.
Where or what could be the problem? What steps should I take? What possible fixes should I try? Thanks in advance