Thank you for replying, because it reminded me to look for actual studies today :) I found this 2023 study that (via a lot of technical detail) basically says it doesn’t matter if the light is blue or yellow. The authors say theirs was a smaller study limited by budget constraints, but it supports what you said. If you scroll down to the last paragraph they say exposure to short-wavelength light (blue-to-yellow) should be reduced in the evening, and recommend phones, computers etc. have various kinds of night modes and that they be used.

So the summary seems to be - there’s a study that says blue light IS hard on sleep, but it’s not just blue light it’s all light with more energy than red/orange light (i.e. the light you’d get naturally at sunset). It’s just one study and a small one, but that may be what you read and it’s a good starting point for further research.