We documented this through same-day testing after a user noticed their $30 Bitcoin purchase executing $2,100 above market rate per BTC. The investigation found Kraken's standard app charges 3.5% (2.5% embedded spread + 1% explicit fee) while Kraken Pro charges 0.25-0.40% for identical transactions.

The catch: Pro doesn't support automated recurring purchases, so users who want DCA automation must pay the 14x premium. Kraken declined to comment despite two requests.

Using their Q3 2025 financials, we estimated this generates $230-460M annually in excess fees across their user base compared to Pro rates.