Looks like a corporate template.
The same sign was posted in an Irvine, CA Costco, back in Aug of 2022
Note: "[Loc Name]", lol
There was related post, in the Delica Forums, Feb 2022
"Dear Mr. Bennett,
Thank you for your email. Costco's business strategy is to sell high volumes at low prices, and fuel is no exception. The number of diesel vehicles is still a small percentage of the total U.S. fleet.
Anywhere we have or will remove Diesel is due to our diesel sales being minimal, and where we believe that we’re better able to serve our members with the converted diesel tank as additional gasoline storage.
We recognize that this might be an inconvenience as you seek the best value when refueling your diesel vehicle. We remain committed to serving you and our other members with the finest quality goods and services in all the product categories we offer. We will be update our website soon for the Concord, CA location.