Variation of current with time in gel electrophoresis During gel electrophoresis, if the voltage of the power supply is kept constant, how would the current in the circuit change over time?

I was wondering whether the electrical resistance of the gel would change over time. There will be migration of ions present in the buffer and it will resist the change in pH. But how does the electrical resistance of the gel change? Can someone explain?
I think this might help you a bit:
https://www.researchgate.net/post/SDS_PAGE_should_be_run_at_constant_current_or_constant_voltage