Vertical bars on LCD display

Hello! Recently I bought a refurbished Dell Precision M4800 and it seems that I have an uncommon problem with the LCD display. Currently I'm using Windows 10.

I didn't recognize the problem at first, but I'm pretty sure that it was here from the start. The wallpaper was mostly yellow and I noticed thick vertical bars that were only a little bit darker than the regular color. I changed the wallpaper and there were no bars, so I figured that it was just a pattern on the wallpaper and forgot about them. But lately, I've been using graphic programs and I noticed the bars again. And then again, on a yellow background while shutting down Windows.

I decided to test this problem on my own, so I displayed various plain color backgrounds. The bars appeared only on warm, light colors. Greys and very saturated colors like magenta are displayed fine (as well as all greens and blues), but then on light pink or the bars are very visible. Then I discovered that the bars are also capable of moving around and changing thickness when I move the image window around. They disappear when I change the color. I can't capture the movement on video, but I'll attach photos.

Then I also started doing other tests. I thought that this might be related to the GPU - I experienced something similar to artifacts once on this laptop, where suddenly when using Photoshop, the bottom half of the screen turned purple. I panicked back then and shut the laptop down, and when the issue didn't come back I just forgot about it. That's why I thought that maybe it was related, but I tried to use an external monitor and the bars weren't there. I also ran the LCD tests that display red, blue, green etc, but the bars weren't there because the colors are too saturated. Then I used the Dell ePSA tool (I also tested the laptop this way when I bought it) and it didn't experience any problems. Dell SupportAssist never detected anything as well.

My drivers are up to date and the seller updated the BIOS at the beginning of this year. The laptop had Windows 8 when I received it and that's when I noticed the bars for the first time. I updated the system to Windows 10 and Windows Update shows that there are no updates to install. The bars are visible in Safe Mode.

Overall I'm very pleased with the laptop as well as the display's quality. I could live with this problem because it doesn't affect my works that much, but I would gladly fix it if it's possible.

Link to the photos: https://drive.google.com/drive/folders/1DAQwvrmMfUyiLXtorp8naCg_saLvyFB3?usp=sharing