Inflation existed for currencies that were on the gold standard too.
There was over a decade of QE which the rainmakers said would totally cause inflation. It didn’t.
Then there were supply side shocks which would definitely only cause transitory inflation. Also wrong.
Then we learned that sentiment causes it, and in the middle of terrible sentiment inflation went down.
Every complex problem has a simple, intuitive, easy to understand wrong answer. It is not an exaggeration to say that we do not know what causes inflation.