Nanny27
I taught in secondary schools for many years and don't recall any type of singing really. I'm not sure when people imagine it would happen. Music lessons? No, students are generally rugged into headphones. Assembly? These are long gone in most schools, reduced to a few notices from head of year at best.
These days secondary schools in England (rest of UK is different?), only KS3 pupils do regular music lessons (and those few KS4 & 5 pupils who opt for GCSE or A level music) and I think they tend to be pupils creating music (keyboards & headphones with a presentation at the end)
In 1960s we did whole school hymn practice in the hall after assembly, and that time was taken out of first period, sometimes ten minutes, sometimes 40 minutes which was all of period 1 then). Academic time these days is more organised. I never thought of this as cultural. Since 1970s it's rare for whole school to be together as there is no space.
School choirs are extracurricular.
Truly, there is no wokery involved, this is the last 50yrs I'm describing.
Sorry, but if you want your children to learn carols, take them to church.