I've tried a bunch of stuff , including custom molded plugs.
The best thing so far are a set of Titanium Flare plugs.
I saw an add on FB and followed up. They are English.
Ordered a pair, pricy 80 bucks , but cheaper than molded , at least in my area.
They work better than anything I have used , and I have used everything.
I use these and 3M industrial muffs so anything I hear is bone conduction.
The audiologist tells me that the concussion and consequent bone conduction is enough to aggravate a tinnitus condition.
I have no stock in the Flare company and derive no benefit from the recommendation .
I've had tinnitus since my teenage years most likely due to shooting with out ear protection when I was a kid , and some really loud music.
Now that I'm at retirement age I try to not worsen the condition, but its pretty bad.
I still am around plenty of loud music, because I am a professional musician , (apart from my trade in instrument repair) and guns are plenty loud too ain't they, I shoot several times a week !
So do what you can , when you can.
Foam plugs don't get the job done. They are not dense enough , the plug needs to seal perfectly, which the foam plugs do very well but their effectiveness is limited by their lack of density.
When you step up to the custom molded plugs you get a good fit and increased density but the seal is not as good because the material is rather hard, so if you use muffs as well as the custom plugs you actually disturb the fit of the plugs with the muffs.
The Flare plugs have a core of metal, and a seal which is made of a high density foam, so even with the muffs the seal is complete and core density is high .
This is the best I have found so far.