All 3 of my M2 batteries have swollen to the extent a slight knock and one side unclips from the drone.
They've done maybe 30 flights each.
My Mavic 1 batteries all did the same but that took a year or so not 6 months.
I think they dislike hot climates.
The actual drone itself though still looks perfect, no damaged guides BUT the swelling does put a lot of pressure on it.