Let's talk about the differences in select by location or select by attributes add to selection between ArcGIS pro 3.3 and 3.4.
For the longest time I have used add to selection if it was already enabled instead of switching back to new selection. This was not a problem until this morning when I ended up with significantly different results to the expectation. In a long discussion with copilot, it was only then I understood that ESRI broke the core logic between 3.3 and 3.4 without mentioning it anywhere in change notes or in the software itself.
I had a difference of 80 features i.e. >30% of the expected number.
Good thing i check my results and don't just take the software at its word.