The retcon of Jakob as Dom's ***spoiler***
... Dom's brother was actually pretty well done.
They crafted a passable explanation of why he'd never been mentioned before and wove it right into the fabric of Dom's backstory which had been in place from the very first film (and elaborated further upon in F4).
Beautifully crafted writing. Aided by the stellar performances of the actors playing the young Dom & Jakob parts.
It's quite notable that for all the usual criticisms I see from people - who seem to have stumbled across this film series in its ninth outing - this isn't one of them.
The Han retcon on the other hand...