Hello! A strange problem occured which I don't know the cause of.

I've been printing with this PLA filament every day for a few weeks now without a problem, ~8 hour prints at 190°C with heatbed at 60°C.
I use Marker tape for better gripping on the bed.

So I was printing a model and it all went fine for the first 3 hours. Then it just stopped printing normally and made a thready mess on top of that.
And ever since, when I try to print something it creates the same mess from start.

As you can see in the image, top is first layers, bottom is what it will produce after a while.
https://i.imgur.com/ihnOaO5.jpg

Do you have any clues what could be the problem? I've googled but didn't find any definite cause, so I'd like to ask for some directions before I spend alot of hours trying to figure it out...

Thanks in advance!