@lukisrAre the text's coming from a number that begins +447802 by any chance?
It is usually down to the host network from your contact supressing Caller ID or it been corrupt when sent across to the UK.
I have seen this especially from colleagues in Manila texting me.
The only think i can think of is ask your contact to contact their network provider.
Also is your phone a personal or work phone? As some work phones are on a system called Mobex which causes issues with international services.
- Xperia 1V - o2 and Spusu
- Pixel 8 Pro - o2 and Vodafone UK