I have the lg stylo 5. I had android 9 then my phone updated to android 10 and now i cant change the background in my text messages. Did they get rid if that option and if so why. I loved it.
If you aren't partial to the default messaging app, you could download an SMS app like Textra. You can customize text backgrounds per contact, from what I remember, and even things like speech bubbles. It's a free app, and I think the Pro version is $1.50 CAD or something. Definitely worth the money!
I also noticed this. I tend not to use anything other than the default as it gets the job done, and most of the 3rd party ones have tons of ads even after paid, and when they don't have ads they lag the phone down or don't have the right features.