For Swedish pre-high-school kids — the vast majority being in Swedish schools that remained open all this year — it was between very difficult to impossible to get kids tested for this virus before school summer vacation started. If such children here had some symptoms for this, the general advice being provided by government healthcare here was inclining people toward keeping the children away from getting tested and out of the healthcare system. If Finland did sort of the same thing — and it definitely did so in parts — then of course the incident of reported cases amongst such children would be expected to be akin since only the same kind of children population would get tested: those few who get access to a test.
The Swedish authorities may try to keep claiming that school children don’t spread the virus, but these are the same authorities that are hostile to mask use to try to slow down the spread of a virus that most sensible experts agree spreads mainly by non-fomite means.