Its the coolant control valve, i just got it fixed under warranty on my 2021 cx5. Mine used to run cold all the time until it got replaced now it runs rock solid just below 210 F.

Mazda would disgaree with you. They even issued a TSB over this and will replace the faulty part if you are in warranty

Thats exactly what it is. Its a $350+ part. Not terribly expensive or hard to replace but still

Not on these cars. There isnt a traditional thermostat, you have to replace the whole water pump essentially, its called the coolant control valve and mazda even issued a tsb for it