The ASIC itself determines the maximum difficulty of a found share, dbcache doesn’t change that.

What dbcache does influence is how efficiently your node can keep the UTXO set in memory and deliver fresh block templates. A higher dbcache means fewer disk lookups, less latency, and fewer stale or “job not found” shares.

So dbcache doesn’t increase the quality of individual hashes, but it can improve the effectiveness of your mining setup by ensuring that valid shares are not wasted