I live in an ECT slow-2g area in Germany, I have Save-Data: on, and my phone is 5 years old. If your site is using React rather than server-rendered HTML, that'

I live in an ECT slow-2g area in Germany, I have Save-Data: on, and my phone is 5 years old. If your site is using React rather than server-rendered HTML, that's usually a bad experience already. Also, if you decide for your users that they are only gonna see a small, poor-quality image rather than your shiny HD video because of some heuristics that you made up and that are not transparent to your users, I think it's good practice to allow your users to overwrite this decision (e.g. the "Load basic HTML" link in Gmail).