12-inch 2017 MacBook screen goes off at certain angles

Sounds like a hardware issue.

That MacBook is either vintage or obsolete, depending on exactly which model and year it actually is.

Getting service for it may be challenging.

Apple may service a vintage Mac and replace necessary parts IF those parts are still available.

Apple will not service an obsolete Mac, though an Apple Authorized Service Provider might. Parts for an obsolete

may not be available.

Apple provides this guidance for service of vintage and obsolete Macs:

Obtaining service for your Apple product after an expired warranty - Apple Support

That is a known issue with the 2016 & 2017 USB-C Apple laptops. That and the dreaded Butterfly keyboard design which had both design & manufacturing defects. At one time Apple had free repair programs to address these issues, but they expired years ago.

It is not worth spending any money to repair any of these Apple USB-C Intel Macs from 2017-2020 for multiple reasons....you found one reason, Butterfly keyboard is another, plus your laptop's battery is likely worn out or even failing. The money spent on repairs is much better spent on a new laptop.

i agree that replacement is the better path today. The symptoms you describe strongly suggest a worn display cable, the one than runs from the display to the logic board through the hinge area.

In Retina displays, the display unit is one sealed assembly. Should any one component go bad, the only way to fix it is install an entire new display assembly. We cannot quote repair costs, but other people posting their experiences here say that the parts+labor cost for a new assembly starts close to US$500.

How far would $500 go toward the purchase of a new computer that runs the latest OS versions?