Since Smush update, image quality has dropped significantly

We recently updated Smush Pro, but now the quality of ALL site images that we upload, have dropped badly. It's like we have set Photoshop to 10% quality. The original images we upload are good, but on screen they are VERY poor indeed. At this stage we may need to cancel Smush.

https://i2.wp.com/www.79design.org.uk/wp-content/uploads/2018/06/lincs-wordpress-training.jpg
This is an example. The quality is poor, but the one we uploaded was perfect.