So they have - how bizarre - why didn't they just time change the original 4x weekly flights. The flights are all now day flights both ways vs the previous mixed schedule - I saw on Twitter that they had a slot "issue" - not sure if they mean they preferred to use the slots for other things or they genuinely were denied the slots they had this winter.

I don't think then that a rerouting will be an option for ~12hrs disruption - but I think you could put in a claim for your hotel night if appropriate under duty of care regs (though another night in Singapore is never a bad thing

For me the times just do not work - I can either rebook for Thursday or Saturday day-time from Singapore - which is terribly inefficient for me leave wise. I may do Scoot to Berlin instead and hop over from there