2013 Kia Optima - Trans issues

major transmission problems, the gear changes are lagging and eventually it will dump it in gear very noticeably.

Sounds bad. You should take it into Kia, may still be under warranty. Don’t know, you didn’t tell us mileage or whether you are the original owner.

Those are supposed to have 100K warranties on them if you are the original owner .

If it is easy to check the transmission fluid level – on some vehicles this isn’t easy to do – that’s where I’d start. Hopefully OP is lucky and a proper transmission service is all that’s needed.