I have the exact same model, with the exact same string of problems (BSODs, random screen shutoffs...). What brought me to this post was a similar hairline crack appearing overnight at the top of my screen from the microphone hole (I think? There's one on each side of the camera sensors) over the bottom of the camera to the top of the screen. Microsoft already replaced my device once for a pixel stuck on green (hours of time lost to service requests and then backing up and re-imaging the new device, but thankful they did it). As a Microsoft surface line enthusiast (a rare hold-out in the computer science academic community dominated by Apple products), I am so disappointed with these issues for a $2500 device.
I am getting ready to reach out to Microsoft support (their default answer through the web-based support claim is it's your fault, you must have dropped it, so give us $600 to fix a problem that will probably randomly appear again) and will update my post once hearing from them.
I felt compelled to let you know you are not alone and to start building a record of these issues on Microsoft's own pages. I wish I would have done more research before dropping the most money I've ever spent on a laptop:
https://www.reddit.com/r/Surface/comments/hptg18/surface\_book\_3\_quirks\_and\_issues/
https://www.reddit.com/r/Surface/comments/imf6b1/surface\_book\_3\_random\_screen\_crack/
UPDATE: After talking to MS support via the phone, forking up $600 was my only resolution... I am utterly disappointed with that answer as I have no more time or money to give to Microsoft... holding my breath that more people file claims and they admit this widespread issue.