It's not a 100% changeover, but yes, 122.675 is the "new" 123.975 this year. However the coordination couldn't be completed everywhere so there will be some holdouts on 123.975 in places in California at least. Best to have both in the scanner.
This pertains to air tanker bases in California. This information is current as of early May, but reflects what frequencies will be in use in 2023.
Bases that are now on the new nationwide frequency of 122.675: Chico, Columbia, Grass Valley, Hemet, Hollister, Fox, Redding, San Bernardino, Santa Maria, Santa Rosa, Siskiyou County and Mojave.
Bases remaining on 123.975: Bishop, Chester, Fortuna, Fresno, Paso Robles, Porterville, Ramona and Ukiah.
Base on 122.875: McClellan.
I expect that all bases will be on 122.675 by next year.