That sounds right. Using the latest figures I can find online, the lowest Premium Bond prize (£25) was £75,665,750 of the total £88,099,800 prizes[0], i.e. over 85%, whereas lowest National Lottery prize (free ticket worth £2) was £2,306,736 of the total £19,891,729 prizes[1], i.e. under 12%. So if you calculate on only ever winning the lowest prizes, the Premium Bond's not too bad notional return is likely to be not that much worse in practice, but the unfavourable distribution towards the headline grabbing large jackpots means the National Lottery's very bad notional return is likely to be significantly worse in practice.

[0] https://www.nsandi-adviser.com/july-2018-premium-bonds-prize...

[1] https://www.national-lottery.co.uk/results/lotto/draw-histor...