Drop Mir
Canonical spent the past years working on the Mir display server; a project which went essentially nowhere even as it continues to limp along. Imagine if they had put all that time, effort and money into improving GTK or heck, building its own GUI toolkit.
Between the Snap debacle and now this Flutter thing for an essential part of the operating system, one has to wonder what Canonical's thought processes are behind these decisions. What are the chances that Google will drop Flutter in ~2 years from now, and leave Canonical to do the maintenance for not just itself, but the entire community it has managed to attract by then?
When it comes to Linux, I'm primarily a Manjaro (XFCE) user, so little of what Ubuntu does affects me. Even so, it does have the effect of making me glad to not be on the Debian side of the fence. Thanks, Ubuntu. /s