My partner's application got delayed several times, due to COVID, refugees from Afghanistan and Ukraine. It dragged over five years.But you said that you've been living together for five years and your partner got PR last year. So you would have been common law at the time your partner got PR.
My partner and I entered relationship and became common-law when the application was under processing.
I submitted my application as a common-law partner after my partner got the PR last year.