Data collection in its self no. Mass surveillance may depend on exactly how that data is processed or used.
We know how the likes of gchq gather data, and the topic is pretty complex as we’re considering various data sources and various ways of analysing it.
The difference between mass surveillance or not I would say is in if they’re looking for crimes without a warrant over the whole population or if they’re looking over a large data set for specific crimes from specific individuals. If you look at the legislation and information available on the scope of their powers it’s generally the latter. You can’t just use the data without the appropriate approval.
Oversight etc has been improved and can imo be improved further, the related laws could also likely be made simpler and clearer.
A good idea I think