In 2025 some 10,000 students switched from separate sciences to the combined sciences qualification. This article covers some of the issues raised. From a personal experience I believe that if a student wants to progress to ‘A’ level sciences then they should study the separate subjects. There is much less content in the combined qualification, the combined examinations are much shorter and I would suggest that the examinations are much easier as a result.
https://schoolsweek.co.uk/bauckham-concerned-over-switches-from-triple-to-double-science-gcse/