@Chinmoku
Disclaimer: I'm not an MD but I do have a medical background and have read obsessively about the auditory system since my own problems started.
My two cents: it seems this might have something to do with the fact that pregabalin specifically is a GABA analogue drug. I think
@AVIYT alluded to this a bit.
Anything that upsets the GABA/Glutamate ratio can affect tinnitus.
If you haven't seen it, this link has a nice schematic showing how exactly glutamate works in the cochlear nerves.
https://researchfeatures.com/2018/05/01/unravelling-cochlea-understand-hearing-loss/
It turns out, though, that too much or (less commonly) too little glutamate can cause hearing issues. This is one reason chronic benzo use (and especially improper withdrawal) can wreck havoc on the auditory system, the receptors can get desensitized over time (hence "tolerance") and the body suddenly as the physiological equivalent of excess glutamate again.
The research indicates that these imbalances damage through neuro-excitation. The good news is that this balance can be eventually be restored though it sometimes takes years in extreme cases (after chronic benzo use or withdrawal, for instance).
The bad news is neuro-excitation is one mechanism synapses are structurally damaged. When a successful synaptopathy drug comes out (e.g.. Intratympanic BDNF, PIPE-505 etc), I have no doubt this should address that, too, though.
You mentioned hearing loss above 8000 Hz, you may be a good candidate for FX-322, too. They mentioned at their last Q and A that they suspect the synaptopathy at the site of new hair cell growth will be improved because of the new synapses that attach to the new hair cells.
Either way, hang in there. There are therapies that will help many of us soon and with time, some of your glutamate imbalance can correct in the meantime.