I think this bug is not related with Discourse but with Chrome new update Chrome 119.0.6045.163.
I share this to prevent and for reference the possible bug reports about this issue in here.
It happens when the bottom navigation bar is used and try to switching app or try to running in the background while the keyboard is opened. It’s probably a calculation issue.
On Discourse it’s happen for example: when the composer opened. On the video you can see it seems the composer broken and can’t be open again, however it is just off the screen and I think cannot focus and open the keyboard again. When I select a text the composer show up.
I tested it with the latest Edge and Firefox. On these browser this issue doesn’t exist.
Also tried other sites like X where the same issue happens on Chrome.
Without using the bottom navigation bar it works fine: