If Chrome is your default browser, then when an external app opens a link Chrome opens it in a new tab in an existing window. We can argue whether that's the right behavior in general, but it's absolutely wrong if you're using Spaces and the Chrome window is in a different space. Chrome jerks your whole desktop to the left, forcing you to the Space where it happens to have a window open, completely ignoring the Mission Control preference "When switching to an application..". It's terrible.
Fortunately there's a fix. Long story short: you set your MacOS browser to a little program that tells Chrome to open a new window. Tabs still work like normal in Chrome, but external links now always create windows and, as a side effect, avoid the horrible Space switching.
That little program is in AppleScript, an ancient, opaque language. (Compiled scripts? Really?) Here's the nut:
on open location theURL tell application "/Applications/Google Chrome.app" make new window activate set URL of active tab of first window to theURL end tell end open location
It's a bit promiscuous with the windows if you're used to the new tab behavior. The ideal thing may be to re-use an existing window if one is visible in the space, otherwise open a new Window. It's a bit of a mystery why Chrome lacks a new window preference.
As seen on StackExchange