my 2016 kia optima check engine light is blinking and won't go over 60mph

Something go wet, likely electrical under the hood. You just have to dry the car out. In the meantime, park the car in a dark place, like a garage, and start the engine. Then look for electrical sparks.

First pull the air filter out and see if the air box has water in it, if it does dry it out and if the air filter is wet it needs replaced, now the water could have damaged the air flow sensor, so carefully drive it to your favorite independent shop to have the codes checked, then they can tell what has happened.

You are not supposed to drive a vehicle with a check engine light that is blinking. It will cause significant damage.

You can as long as you’re taking it to get checked over but you have to be careful, no full throttle starts, just easy on the acceleration. If you get nuts with it the system will go into limp in mode then your stuck with 25 mph.

Again with the errors

The engine is misfiring because the ignition system got wet. That's why the check engine light is flashing. It's warning you that the catalytic converter is being damaged from the misfiring. Hope that helps! Jim