I also found that cookie banner to be unnecessarily large in size.
The answer from SE so far says:
"we need the cookie banner to be visible enough that it won’t be missed.
but it can still be visible without covering up important buttons.
Indeed the EDPB guidelines say:
"Cookie walls (i.e. forced consent conditional for access to a website) cannot be considered valid consent, because user consents must be freely given and specific."
and the cookie banner on SE does force users to allow the "mandatory" cookies in order to rid themselves of the banner.
The answer from SE also says:
"Our goal is to collect user preferences, whether they would like to consent to cookies or decline them"
but some users may not want to give their preferences (especially if they think that not clicking any button at all may avoid them from allowing the "mandatory" cookies too). Others may be on a work computer or a library computer and need to check an answer to something quite quickly, and may not want to go through the hassle of providing their preferences.
While inconvenient, at least on desktop browsers it's possible to zoom in and out until the banner's placement relative to other features of the site is not as invasive. For example, the cookie banner in the lower-right corner would prevent me from clicking the "chat' button, but if I zoomed out just enough, I'd be able to click the chat button again. Zooming in-and-out is fairly easy either with CTRL+Plus or CTRL+Minus on the keyboard or moving the mouse's wheel forward and backward while holding CTRL on the keyboard (i.e. it doesn't take *too* long). Hopefully this will help for the case in your screenshot!
What was most inconvenient for me was the cookie banners in the mobile version and clicking "full site" or switching the browser's setting to "desktop mode" did not help. The worst was that I could not properly do reviews, because the buttons were behind the cookie banner. In the end I followed this user's advice and installed ublock on my desktop, and to install it on my android device I needed to actually download and install Firefox for Android for the first time because ublock doesn't work with Chrome on Android devices.