Xiaomi Powerbanks really low quality, only good thing is the affordability.
Over the years I've owned:
First Gen 10k - very short life span, battery 70-80% life by 8-9 months despite light usage (1 week only used up 100%)
Slim 5k - similar experience as the 10k but symptoms show much earlier around 6-7 months.
Pro 10k - Swollen after less than 10 months of ownership. Light usage, only use it 2-3 times a month during travels.
All my Powerbanks are well taken care of and kept indoor under room temp when not in used. Despite this they still cannot tahan.
My current main PB is a Pineng 6k model, its been good so far after 14 months. If it continue to be reliable then I will continue to support the brand in future.