It’s not just the UK. The ammunition shortage has been widely reported:
“NATO Secretary General Jens Stoltenberg said on Monday that the “current rate of Ukraine’s ammunition expenditure is many times higher than our current rate of production,” which is putting “our defense industries under strain.”
Link: https://www.cnn.com/2023/02/17/politics/us-weapons-factories-ukraine-ammunition/index.html
More:
https://www.politico.com/news/2023/02/14/u-s-training-ukrainian-troops-use-less-ammo-00082765
https://www.dw.com/en/ukraine-war-is-the-army-running-out-of-ammunition/a-64710592
You can do an internet search and find many more.
I wonder how the PRC’s ammunition supply is holding out?