I'm writing a formula in Excel (Microsoft 365) using the LAMBDA function and happened to name a variable mat1. This resulted in an error and I noticed that the name mat1 was a different colour. I tried writing =mat1 in a cell and weirdly it's equal to 0, rather than causing a value error as expected.
I checked the name manager and it's empty, and the workbooks doesn't have macros enabled. I also noticed that mat2, mat3, etc. are all equal to 0, as are arr1, arr2, arr3, etc.
Why are these variables defined?