I don't agree with this. I use Google Photos to upload all my pictures and videos and it also gets killed when in background. Apple's iMovie app literally asks you to not put the app into background when rendering the video. This shows that apps in background will get killed mercilessly. Some Apple fans might argue this is better for battery, but it feels so primitive for me in 2021 to use a "smartphone" only to use one app at a time.

Try sending media in whatsapp or post a media in Instagram/Facebook in low network condition and putting the app in background. It is literally impossible to do this in iPhone.