Also take a picture of the whole shower because if this is wrong, I'm guessing the rest is wrong.

Stop now and get another person to build, waterproof and tile your shower. All cement board joints must be taped with alkali resistant tape and thinset and the Redguard should be consistently applied to the required thickness. FYI the use of Redguard is often a sign of an amateurish approach as it is purchased at your local big box home improvement center and there are better products available through professional outlets. Look for a tidy and uniform finish like this.

This is one of the most unprofessional jobs I've seen and is a huge leak with mold waiting to happen if you continue with these amateurs.

Thank you for your input

Don’t hire another $500 handyman. You want the 5K tile professional. If you stay with this guy, the mold and rot is on you.

https://www.ceramictilefoundation.org/blog/hire-a-tile-installer-roadmap?hs_amp=true

I've looked at that exact website, thank you! Not really anyone near 95007 🙏

Plenty of the best tilers in the santa cruz and surround area.....and 5K not enough ! Id suggest getting on Instgram and search tags/locations

Or go to an independent tile store and ask for who they recommend.

Call Mission Tile in Santa Cruz (http://missiontileinc.com/) and ask who they recommend. Or go on NextDoor and ask for recs there -- but specify that you want someone with a license and insurance. You can also call a contractor (we used Costa Bella; they're great) -- they prob wouldn't want a small (although getting bigger, unfortunately) job, but they might be willing to recommend someone.