what is this brown viscous fluid that builds up in my dry herb vape?

I looked to find a decent 101 on dry herb vapes but alas the enshittification of the internet continued and I couldn't find any sites that aren't also trying to sell something.

So in addition to wht others have explained, here's a bit of extra info from the best two pages I could find:

https://www.planetofthevapes.com/blogs/blog/how-to-vape-dry-herbs-for-beginners

https://thevape.guide/how-do-dry-herb-vaporizers-work/

Dry herb vaping also advantage of working with plain flower so you know what you're vaping as opposed to refined vaping products like juices, waxes, oils, etc. which can have additives that aren't so good for you.