4g slower and less prevalent since the roll-out of 5G in the UK?

Until 5g was rolled out a few years ago, I got strong 4g connection almost everywhere in cities, with high speeds. Then since 5g came out, 4g has felt much less widespread and on occasion a lot slower. For example, I used to consistently get full bars in my house and now I rarely do. This is all anecdata of course, but it's a very clear difference

But then almost everything I can find on the internet denies that this is possible. No 4g towers have been taken down, no throttling, nothing.

What could be going on?