For routes operated by RAPTDev (London United & London Sovereign but not Quality Line as far as I can tell) there seems to be a MAJOR issue with the predicted arrival times.
As I type:
SP40130 (YT59PBY) on route 281 is shown as due to leave Hounslow Bus Station at 17:09 and will reach Tolworth by 17:30.
DE20131 (LJ16EXN) currently at New Malden The Fountain at 17:00 and will reach Putney Bridge Station at 17:14.
LT171 (LTZ1171) Due to leave Hammersmith at 17:06 and reach Kings Cross by 17:31
VH45103 (BD13OHW) Due to leave Golders Green at 17:03 and reach Lancaster Place / Somerset House by 17:28.