Replaced the battery in my Google Pixel 3 today.
Had noticed a few days ago the volume down rocker didn’t register anymore. It’s used also for screen shots.
When I took the case off the (glass) back was bulging and most of one edge had the seal separating.
Temporarily I: 1) left the case off for better cooling, 2) turned on battery saver mode and stopped using YouTube to reduce battery discharge rate, 3) changed charging strategy to charge only at 1amp rate and charge only to 80 percent. (I have never charged using wireless capability, but if I had I would have switched to only USB cable charging.)
Also avoided placing the phone anywhere that a fire or explosive disassembly would be unwise. Also, never charging unmonitored.
I ordered a new replacement which was estimated to arrive tomorrow, but when the estimate changed to arriving on the 30th I ordered a replacement battery.
Pictures of old battery after replacement, taken using repaired phone: