Screen is flashing black to the point it's unusable.

Please refer to this for visuals.

Some weeks ago, my MacBook Pro 2018 (Touch Bar) started acting weird. I was back from the other place so I couldn't care about a single black-flash or two and watched some movies. However, it got worse when using those full-screen or heavy applications.

And I had to go to another country so I brought my other Laptop with me. But when I came back, I did some troubleshooting -

• Ran in Safeboot
• Ran in Recovery Mode
• Reseted NVRAM and SMC or whatever
• Wiped the entire disk and re-installed Sequoia
• Downgraded to Ventura

All of those results in the same flashing black.

Then, I thought it was the cable since the disk was wiped clean and it was a fresh install. But however, whenever I'm running CleanMyMac and stuffs, it doesn't seem to do that thing. The same when watching live from Twitch or Youtube in full-screen mode.

So, I'm still confused if I should be reseating/replacing the cable.

But yes, tilting the lid and leaving it at about 45 degree (almost-close lid) seems to solve the problem but all I could do in that angle was press enters on terminal.

So my questions are

1. Is this a confirmed cable thing or is there any fix that I missed?
2. Is reseating/replacing cable doable by a non-Apple-tech? (I have experience with Windows Laptops but I'm afraid Macs would have different structure although I do know they will also have similar structures)