Laggy iPhone 8 Plus

Does anyone have any experience with what would suddenly cause my iPhone screen transitions to become laggy and glitchy in appearance. It started around the same time when I started getting menus popping up at the top of my screen from time to time offering me different “commands” to use from time to time and will sometimes also say that voice is not active, and then say voice is active. I’ve checked Siri and it seems to be working normally - but screen transitions are not smooth at all, and it’s a very recent change in behaviour. My storage isn’t even half way full. I haven’t installed any strange apps recently except for Call of a duty mobile. Even when that was uninstalled though the lagging persists. I’m happy to hear your ideas. Thanks.