As best as I can tell, there is a small change in behavior in the FileMaker Pro calculation engine which occurred between v.19.5 and 19.6.1. Please note that I have not tested to see of this change occurs across all FM Pro platforms -- I have only investigated this on MacOS (12.6.1).
Behavior that I have always observed and expected is that many/most functions and operations in the FM Pro calculation engine return values which have an associated data type that corresponds to the result type of operations.
There are some operations which one intuitively expects to return a value of type Text, such as the result of functions such as Substitute, Left, Right, or concatenation with the & operator.
There are other functions/operations which one intuitively expects to return a value of type Number, such as the result of the function PatternCount, or Position, or the result of using the arithmetic operator +.
Change Between 19.6.1 and previous versions:
In versions prior to 19.6.1, the Trim function returns a value which retains the data-type of the input value.
In contrast, in v19.6.1, the Trim function seems to always return a value which has a data-type of Text.
It's a nuanced change, and for those of us who tend to explicitly cast values when there is any chance of uncertainty about the data-type, it is not likely to cause any issues. But, if you find yourself maintaining some code that makes assumptions about data-types, this is the sort of change that could result in code breaking with an update to v.19.6.1.
I experienced this today with a solution that suddenly stopped working properly because a value which, prior to 19.6.1, had been treated as a Date, started being treated as Text when the FMP client version was updated to 19.6.1. The solution was to patch the calculation that was making an assumption about a variable's data type. It took me some time to track down the cause of the issue, hence I figured I'd post a heads-up to my friends here at the Soup, in case it saves anyone else some detective work.
Some screenshots below attempt to illustrate. The screenshots show a comparison between v.18 and v.19.6.1. That said, I believe that the change actually happened between v.19.5.4 and 19.6.1.
Also, to reiterate, I have only focused in on this matter on a MacOS machine (though, given the nature of the issue, I suspect that this will be change be present across all supported platforms.
Hope this helps.
Behavior in v.19.6.1 of FileMaker Pro
Behavior prior to v.19.6.1 of FileMaker Pro