Great suggestion !
Before posting this topic, I had enabled safe mode and still encountered the problem : thus thought it was not due to plugins. However, it seems toggling safe mode takes effect on Obsidian reboot !
To make it short, problem described in this topic only happens when Emoji toolbar plugin is enabled. Either I don’t use it properly, or there’s a bug (or unimplemented behavior). In any case, I have opened an issue to its github.