Her album sales are fine/decent, but I feel like she should be doing more for all the effort she puts in (including all the huge smashes).
At her peak, Gaga sold more with fewer smash hits; Rihanna doesn't sell that much less, even though her eras last less than a year; Beyoncé sells fairly well without any hits, and even better with hits; etc.
Still nothing to scoff at though considering barely anyone is selling anymore
Her single sales are way more than respectable.