iphone 12 mini camera picture quality

I recently bought an iphone 12 mini, mainly to update and to get a better camera (I draw and take a lot of photos of flowers and plants). I have noticed a problem. The picture on the screen looks great and if, for instance, there are yellow flowers on a green bush they stand out nicely. However, as soon as I click the share icon (to either email, air drop or whats app an image) the photo suddenly looks much duller. This happens whether it is on Live or not. I tried a screen shot and the same happens. We have experimented and my husband has taken the same flowers (on both live and non-live) on his iphone 8 and this dulling of the picture does not occur. Anyone know what is happening?