The speed force was retconned since Bart absorbed it all. In Bart's series i remember that the full destructive capability of the SF was continent level. Although there are previous stories which show it being far more than that, the SF has been retconned since then anyway.
Initially the SF was merely a heaven-like realm for speedsters and is the realm from which they draw their energy from. Then it was retconned into being a source of energy that encompasses the multiverse (see Darksaint's scan); this was then expanded upon to reveal that the SF literally stitches space-time together: https://imgur.com/a/BccMlst