Hey Ilya,
The calculated attribute requires a microflow to run, and it doesn’t matter where the microflow is, the calculated attribute will trigger the microflow, every time the conditions for its recalculation meet.
Hope it helps and clears your confusion!
Each time an object with a calculated attribute is retrieved, the calculation microflow is run even if it’s not used.
https://docs.mendix.com/refguide/attributes/#value
Have a look at Mendix best practices MXP001 and MXP002 for more information on the best way to use or remove calculate attributes from your application.
https://docs.mendix.com/refguide/performance-best-practices/#mxp001
I hope this helps.
When the microflow updates 50 objects they are sent to the client. When the microflow updates 100 objects they're not sent to the client and their calculated attribute is not calculated. This behavior isn't documented.