she had indefinite leave to remain (permanent residency), the only condition to keep it is you have to visit the UK at least once every 2 years, she then spent 8 years outside the UK without visiting, so she lost it.
she had the option of taking UK citizenship after five years residence, but chose not to as Singapore doesn't allow dual citizenship. she wouldn't have been granted government accommodation in Singapore as she would be a foreign national
the UK border force is literally blameless here, if anything they were over-compassionate in granting her another visa after she overstayed previously, which lead to the eventual detention and deportation
The title seems almost cynical when she could have avoided this whole ordeal had she followed procedure, which she admits she was familiar with.
Also, blaming this on "Brexit UK" is transparently inflammatory since the requests for leave were made, and rejected, a decade before Brexit was even a question.