Parashas Bamidbar
כׇּל־פְּקוּדֵ֨י הַלְוִיִּ֜ם אֲשֶׁר֩ פָּקַ֨ד מֹשֶׁ֧ה וְׄאַׄהֲׄרֹ֛ׄןׄ עַל־פִּ֥י יְהֹוָ֖ה לְמִשְׁפְּחֹתָ֑ם כׇּל־זָכָר֙ מִבֶּן־חֹ֣דֶשׁ וָמַ֔עְלָה שְׁנַ֥יִם וְעֶשְׂרִ֖ים אָֽלֶף׃ {ס}
All the Levites who were recorded, whom at GOD’s command Moses and Aaron recorded by their clans, all the males from the age of one month up, came to 22,000.
Torah Temimah points to TT / Midrash (verified).
ואהרון — תניא, למה נקוד על אהרן? לפי שלא היה באותו מנין.
English: “And Aharon” — it was taught: Why is there a dot over Aharon? Because he was not included in that count.
Custom
Chazal explain the dots over “Aharon” as signaling that he was not part of the Levitical total.