Took awhile to identify this tool. To rediscover its origin (it was installed 2.5 years ago & I’ve slept since then), it was necessary to uninstall and find where the App was proffered.
Yes, it was the Chrome PWA. Reinstalling cleared the Gesture oversensitivity for Swipe-up.
If a developer has to do anything to make the Discourse PWA for hosted sites “installable”, perhaps there is a registration or string setting to make the App Info’s provenance more explicit?