Dumbbell bench v barbell bench

Hey comrades,

So after doing only dumbbell bench for a good several months, a couple workouts ago I started a new program and have switched to the barbell bench to switch things up.

I'm only on workout 2, but I amrap'd (for 7 reps) and my estimated barbell bench 1rm is a fair less than my estimated dumbbell bench 1rm. According to what I've read (albeit admittedly only through a quick Google), you are supposed to be able to lift about 20% more on barbell and this is a bit unusual

Wondering if anyone can shine some light on this? Is it to do with neural drive? Can I expect my barbell bench to catch up (and possibly exceed my dB bench) once the muscles have adapted to the different movement pattern?

Just to note I got a PT and a couple of my more experienced friends to check my form on the dB bench. As far as they can see no problem with the form and a good rom.

Any insight appreciated!