Washington is probably somewhat less susceptible to a red wave at this point, since voters tend to be relatively engaged, and the Seattle area is the kind of place where the Republican brand is extremely toxic at the national level (less so at the statewide level), so even many voters who aren’t crazy about Biden are still not likely to vote Republican.
This is all seems.... very cope-ish? You could make this argument about anywhere in the country. WA is no more engaged than any other state. You can't just use the result in WA and just say "oh well its happening in WA, but nowhere else!"
If anything, the results in WA thus far bear out the fact that the GCB is equal right now.
And if the Republican brand is as toxic in the Seattle/suburbs as you claim, that Democrats have a great chance of keeping in the house in the fall then, since many seats reside in those types of areas.