Virgin Media O2 are closing their 3G network by 2025, so like other networks customers are going to need at least a 4G compatible phone to then use apps successfully.
https://news.virginmediao2.co.uk/vir...twork-evolves/
As a reminder all 2G networks will go in the UK by 2033.
EDIT: Realised I've put this in the wrong place - was supposed to be in the Mobile section.