I have two things for you to try which may help, a Forced Restart and updating your iPhone.
First, try a Forced Restart which will get rid of any corrupt software files which could be causing this. Be sure to perform it quickly and ignore the Power Off Slider that appears midway.
- Press and quickly release the Volume Up Button
- Press and quickly release the Volume Down Button
- Press and hold the Side Button until you see the Apple Logo
Then considering that you are behind about 3 years of updates, you have missed out on a lot of bug fixes and performance enhancements. That's the next thing I will suggest, updating to the latest iOS 18.3.2 in Settings > General > Software Update which could fix this.
If the issue is still occurring, please post back.