Update: Apple released iOS 11.2.5 beta 7 on January 19 which appears to be the golden master. The official release should come the week of January 21.
Apple Pay Suica performance tweaks in iOS 11.2.5 are holding steady in the beta 3 release. JR East also released a special Mobile Suica system maintenance downtime notice today. Major maintenance will be done January 30 from midnight to 4 am. There is also special iPhone only Mobile Suica maintenance scheduled for the early morning hours on January 18.
Maybe it’s nothing but the timing feels like a perfect fit for the official iOS 11.2.5 release: January 18 Japan/January 17 USA