It can be hard to tell what is going on from photos. A likely culprit is sunscald, but blossom end rot is another possibility - especially if the damage is at the bottom of the pepper, which it looks like it is in two of the photos. This source from Utah State University Extension has some good information on blossom end rot and how to prevent it: https://extension.usu.edu/pests/ipm/notes_ag/veg-blossom-end-rot

Some information on sunscald: https://pestadvisories.usu.edu/2017/08/31/sunburnsunscald-in-vegetables-squash-diseases-spider-mites-sap-beetles-corn-earworm-new-fact-sheet-and-upcoming-events/

If you have further questions, please contact the master gardener desk<personal data hidden>. you can bring in a sample for us to look at. We're located within the Mesa County Fairgrounds and are open 8am-5pm.