technically, of course, undo would be possible, however, it is not implemented and would be quite some effort - so out of scope for a “quick fix”.
also, as @Simon pointed out at Feature request: import old messages (assuming you have the keys), undo also has its ux issues and may fail expectations of eg. activists. of course, that can be mitigated, maybe by a timeout, a special button, however, this again increases effort and complexity of what users have to understand - and some risk will probably remain by the nature of undo.
for both reasons, i would not target undo for now.