Undercutting salary?

My boyfriend has had an interview this morning, the job was advertised at £40K, the recruiter confirmed via Indeed that the role was £40K when arranging their interview. He told them his currently salary, which was £35K, and they agreed they would be able to get him more.

During the interview with the company. They’ve told him they don’t want to pay big commission to the recruiter, so have said they’d pay £30K for the first 12 weeks, then “if they’re happy” will move him to £35K.

Am I going mad, is that not an absolutely wild thing to suggest? Surely everyone else who has applied and interviewed for this role has also done so under the guise of it being £40K?