This isn’t a change, it has always been a latent exploit.
The only thing you need to do to avoid the “UK/ANZAC” stub move here is to leave the units on their transports.
Since you always have a substantial fleet in SZ 36 (for example) covering the TTs to prevent their destruction, there is not really a risk here. The only opportunity lost is the option dumping the troops off in Kwangsi of using the transports to bridge/run up north on your next turn, rather than invade islands, Malaya, india etc. But, since you moved the TTs down to SZ 36 in the first place, there is little reason to reverse this direction…
Also, the UK/ANZAC early declaration of war “decouples” America from the alliance. UK often does this in order to get NOs. Once this occurs, there is no “tripwire” besides the fall of London to bring the US in.
As you guys have discussed, Japan attacking early brings the US in big and early, and often 100% pacific, since many good J1 strategies involve intimidating and warding the US navy off. Waiting till J3 or J4 seems unwise, unless you have some kind of gambit brewing, because
you cannot reach threshold income during general peace
UK and ANZAC should be quite tough by J3 or J4, with plenty of unabated income
you only get to attack Russia and China in the meantime, which doesn’t advance goals except possibly the G2/I2/J2 Russia-crush.