Are ballooning batteries a widespread issue with the Deck?

Hey folks, just something on my mind. I bought my Deck around November of last year, and since joining the subreddit I've been kind of alarmed at the frequency people seem to be having their batteries balloon. It's gotten to the point where I'm constantly checking mine for any obvious deforming on the back plate and being concerned about leaving it docked for too long.

So my question is, how common actually is this issue? I saw somewhere there was apparently a batch of bad batteries at one point in the Deck's release, but I'm wondering if this is a case of seeing it a lot on this subreddit is giving me a false impression of it's commonality.

I realise this has likely been answered a million times and it's probably me being paranoid, but it might help to get a clearer picture (at least within this community) of how high a chance of it happening is!