Change of price after booking request [Brazil]

I'm a long time user of airbnb. It's the second time in a row that that host is trying to raising the price (this time is 20%) over the one advertised , stating it's an error. The first time (a month ago), I agreed to it , it's the apartment where I'm now. I thought it was unfair, but didn't want to think too much of it. Now this second time, I wonder, is this a justification for some kind of flagging or reporting to the platform, or is it now a commonplace thing. I've sent a request to book an apartment (not instant booking) and got a reply that it was an error, that now it's 20% (with apologies attached etc…)