Hundreds of 'normal' styles in calc

Why do I have hundreds of ‘normal’ styles in Calc? I can’t be the only one but I can’t find a reference to the issue.

Parts of the spreadsheet were originally from Excel so I suspect that may play a part.

I haven’t done any real troubleshooting because it’s a nuisance but doesn’t impact functionality or noticeably impact performance and I wouldn’t know where to start getting a baseline then tracking when it occurs.

Update - Sorry - should have tried this before posting. I thought I’d tried deleting them before but maybe not. I’ve selected and deleted them all and will update the post if they start reappearing.

The Delete option is grayed out when the style is applied.