I tested two extensions and all of them got affected.
Top and Bottom scroll buttons
After installing this extension, I can see a grey button at the right edge of page, and the button is always centered, but after I zoom on touch screen, the button is pinned at a specific position and it was no longer centered.
Scroll To Top
After installing this extension, I can see a blue button with arrow always at the right below corner of page, but after I zoom on touch screen, the button is pinned at a fixed position.
I tested two extensions and all of them got affected.