That should just be a calibration / receiver issue. If you have a center channel, it probably isn't set loud enough relative to the other speakers. OR if you have surround channels, if they're set too loud, they'll drown out the dialog. Same for an overcranked sub (most people's subwoofer setups are totally atrocious; if they get absurd thump thump, they're happy).

Different receiver processing modes will also be more or less successful. I found that the DTS Neural:X mode muddied the dialog while Dolby "DSur" was much cleaner. If you have a two-channel system (only right/left speakers), how the receiver downmixes to stereo can affect how the dialog is presented.

My ears aren't great at deciphering speech (I can never understand anything anyone says in a loud bar), but calibrated speaker levels are vital (lots of receivers have things like Audyssey calibration built-in where you place a microphone at the listening position while it chirps out test tones). On top of the calibration I usually dial in a +1 dB boost to the center channel.

But overall what you describe almost definitely isn't a blu-ray issue; it uses the same audio data format as streaming services (Dolby Digital, DD+, Dolby Atmos) and even regular DVDs (plain Dolby Digital).

Though maybe it's one of the additional formats (e.g. DTS Master Audio) that could be on a blu-ray. Maybe something about that kind of format + your receiver is just a bad combo.

Another possibility is if the blu-ray player itself is processing the audio and screwing up the levels.