If the Japanese troops are sufficiently numerous, acclimated, competent, and arrive in place with sufficient logistic resources prior to November 1915 and the Turkish repulse of the British forces at Ctesiphon,
https://en.wikipedia.org/wiki/Battle_of_Ctesiphon_(1915), the Allies may be spared the defeat and humiliation of the siege and and surrender at Kut al-Amara, and possibly victoriously completely the Mesoptamia campaign a year earlier than OTL.
Ooh, that timing, against that enemy - the Turks - would sort of show up the strongest objectors to the racial equality clause - the Australians under the Billy Hughes government, because it would be in a similar timeframe as the Gallipoli evacuation. [Racist as he was, Wilson was not the primary objector to the clause, Australia, South Africa were, possibly Canada as well - because they were the most panicked about Asian immigration being affected by an equality clause. I have the feeling Wilson figured anything could be declared but it wouldn't trump US domestic law.]
Doesn't mean they'd get the clause. Might make the British think harder before discarding the Anglo-Japanese alliance. [which ironically, the Australians favored continuing, even while the Americans opposed].
The Japanese might be more insistent about the racial equality clause in this ATL though, make a bigger stink, threaten a walk-out. Or they might feel more entitled to stay permanently in Qingdao. Or entitled to enforce the 21 Demands on China. Which can cause all sorts of trouble.
Or if it causes nothing so dramatic, it could still have some lesser medium and long-term effects - a cadre of Japanese converts to Islam, more ties between Japan and future Iraq and Iran and Kuwait.
It would not be unreasonable, although it is certainly not guaranteed, for a sufficiently early and successful Japanese expeditionary force (JEF) in Mesopotamia, accelerating the success and completion of that campaign to link up with the Russian campaign from the Caucasus into northeast Anatolia/Greater Armenia at some point in Kurdistan, doing a lot of damage to the Turks in the process, allowing redeployment of British forces west to the Palestine front, all resulting in early death/capitulation of the Ottomans, possibly saving the Russian war effort from death by Bolshevik revolution.