What I did: since the last update I’ve had problems with Agenda applying strikethrough formatting on its own without me doing anything
What happened: this happens sometimes when I’m typing and also when pasting text — the strikethrough formatting is applied automatically without me doing anything.
What I expected: I don’t expect strikethrough formatting unless I do it myself 
Things that might be helpful to know (Agenda version, OS and model, etc): I’m using 2.11 Mac App Store on High Sierra 10.13.14.
Could this have to do with the fact that the shortcut has changed to cmd-S and you, perhaps even without noticing, press cmd-S all the time (a routine from being afraid a crash won’t save your documents, which I notice I sometimes still do myself once every while – and just to be clear, there’s not even an explicit manual save in Agenda, it always auto-saves)?
If this happens to you again, and the note is not personal, could you perhaps export that note as Agenda Archive format and send it to us? We would like to investigate this issue more.