How does the input voltage affect the current consumption of a microcontroller?
This really depends on the implementation of the microcontroller and cannot be answered in a general way.

Some parts will always be affected by the supply voltage, for example the dynamic power consumption of GPIO when they are switching.

Some microcontrollers have internal voltage regulators for the core or other parts of it so they will internally run on the same voltage all the time, rendering the effect of the external supply voltage minimal.

Others don't have this and their power consumption will depend on the supply voltage. But still they usually only give figures for current and not power.

That is because the tables are for specific use cases which are usually either written on top of the table or below the table. In most cases it will contain something of "Ta = 25 °C, VDD = 3 V unless otherwise noted".

For example a note from the STM32G0 datasheet:


Some manufacturers will provide detailed plots or tables for different scenarios but as the combinations are incredibly complex, you usually only get one thing and have to measure all the rest yourself if you really need it.