Why does the tab preview need proxy permissions?

[portiatrivisonno]

When enabling the tab preview (Settings -> Tabs -> Tabs preview -> show tab preview on mouse over) Sidebery asks for two optional permissions:

• Access your data for all websites
• Control browser proxy settings

I can reason why Sidebery needs the first (to generate some kind of "screenshot"; is this true?), however, I'm very skeptical about the proxy permission.
Why does Sidebery need it, could you please explain? Thank you.

[mbnuqw]

Because I'm lazy to separate these permissions, it's kinda lots of work with zero benefit for myself. Maybe later.