Data Validation list and Month display

Even the Microsoft folks were stumped by this example......

I have a data validation drop-down to display the 1st of every month in a year. When using app version, dates display correctly (7/1/2021, 8/1/2021......). However when I open in browser (SharePoint), dates display incorrectly (7/21/2022....)......which messes up my index/match results. I believe it has something to do with regional formatting rules but not sure. Any ideas?

That works fine for me with Online using One Drive.