Font formatting of a calculation dashboard KEEPS reverting every time the data in the other sheets is updated

I am at my wits end, every time I open this spreadsheet the formatting of these cells (supposed to be large and extremely readable to low-tech users on same team) reverts back to Calibri size 11 for some reason. I even created a custom cell style to try and force it to stay that way and I can see that it's selected in the menu, but not reflected whatsoever.

Is it just impossible to format cells with a constantly changing calculation? What can I do here?? I feel like I have gone through every formatting constraint/rule there is to try and force it to behave but it always changes back, even if its not right away.

It's a spreadsheet stored on sharepoint primarily but I don't know if that makes a difference. Advice appreciated. 😞