Check the actual model numbers, it’s on the back of the brakes and on the side of the lever body under the hoods.
That will at least give us a starting point to comment from. Shimano have changed lever and calliper ratios over the years from ‘standard’ to SLR to Super SLR and then ‘new’ Super SLR.
It’s complicated if you’re not aware of it and easy to make a bad match but fortunately Shimano tech docs are pretty comprehensive and archived over the last 20 odd years so the information is available. They have even produced compatibility tables to help people work out what will work with what.
FWIW if you’re running say 6800 levers with 6600 brakes then they will run with extra clearance, feel very firm at the lever but be shit for actual braking power as that’s a bad match, akin to running cantis with V brake levers.
If you’re running compatible parts then it’ll be down to cables and pads (and rims to a lesser degree), but let’s check parts first.
I’m sure I’ve even chatted with you about this in an old thread at some point.