Stale data with fallbackData, keepPreviousData and disabled revalidation

[alexanbj]

Bug report

Description / Observed Behavior

This bug occurs when using the new keepPreviousData option (in v2 beta) together with fallbackData and disabling the automatic revalidation features. The first time you switch back to the "initial key" the returned data doesn't update. It belongs to the previous key.

Subsequent key changes back to the initial key works fine. Note that this only happens when disabling revalidation When using the default revalidation settings this doesn't occur at all.

Expected Behavior

See reproduction.

My use case here is that I don't want to refetch the data on the client when mounting. The fallbackData is fresh/retrieved during SSR.

Repro Steps / Code Example

Check the checkbox and the data filters, uncheck the checkbox and the data is stale. Further toggling/key changes works as expected.

https://codesandbox.io/s/exciting-agnesi-e704i2?file=/src/App.js

Additional Context

SWR version: 2.0.0-beta.6

[koba04]

@alexanbj Thank you for your feedback! I've created a PR to fix this. #2169