In the previous major version of apollo-client, you could import buildDelayFunction from https://github.com/apollographql/apollo-client/blob/main/src/link/retry/delayFunction.ts. That was handy if you wanted to sometimes override the default behavior but then fall back to it in other cases. As an example, you could consider Retry-After
headers when present, but otherwise invoke the default delay.
It would be nice to either re-add the export of that utility (also maybe buildRetryFunction), or to expose them in some other way so that we don't have to rebuild jitter handling and whatnot.