I'm guessing it's insufficient space between the spacebar and the navigation element and you are pressing in slightly too low and it is being misinterpreted (only a guess as I don't know which version of navigation you are using on the S20, there have been 3 in recent years!). If your keyboard allows you to resize or move it slightly that might help, once you have got used to the shifted position.
I've not been impressed with Google's "gesture" navigation. The current version is basically a second-rate clone of the iOS navigation, right down to the visual style, plus a bolt-on for the system "back" gesture (which iOS lacks). It's less fluid than either the 2 or 3 button navigations which preceded it, due to the need to pause in order to distinguish "home" and "recent apps" gestures, with the extra possibility of confusion between those swipe-up gestures and the one to bring the app drawer. And the "swipe from the side" back gesture can of course conflict with other side-swipe gestures used for navigation in apps or the launcher, plus of course makes "swipe from the left for the hamburger menu" (Google's own interface, though I think they are now trying to phase it out) very difficult to use reliably even with the "sensitivity" adjustment they added. But I've enough experience with iOS navigation to see that whatever they claim about doing their own design they really have just tried to make it as iOS-like as they could, which is frankly very weak and added to my loss of respect for them (on iOS there are fewer conflicts as many of the conflicting elements don't exist, and while there is a lack of fluidity in the "recent apps" gesture, because it's the same "swipe and hold", the previous "double click a button" was never the most fluid thing so it's less of a loss

). Frankly I think that if they'd taken the "2 button" navigation of Android 9 and replaced the "back" button with a "swipe the pill to one side" (and let the user choose which side) gesture it would have worked far better than the current thing. But it wouldn't have looked like an iPhone...