Large SharePoint list, filtering by date modified show incorrect data

I have a SharePoint list with 40,000 items. I created a view that filters on the modified date greater than [Today] - 5. The modified column is indexed. The view loads, however, the results include items with a modified date as far back as 12 Oct 2022. The current date is 14 Feb 2023. 

I get the same results if I use a specific date in the filter. When I filter by Created date, the results are correct. I also see weird behaviour if I change the filter to "Modified = 08/02/2023" (Feb 8 2023 - locale is correctly set to Australia). The 309 results include approx. 100 items between 5 Dec 2022 and 9 Jan 2023

I'm not specifying any additional filters, just the Modified date. I realize that it is a very large list, but we have factored that into the implementation.