Quick answer: Bug bashes find bugs; UX bashes find friction. Each needs a different test plan, different testers, different reporting.
Bugs and bad UX are different problems. The bashes for them differ too.
UX bash separately
Different testers (UX-focused); different reports ('felt slow'); different triage.
UX-specific tracker tags
UX issues tagged separately. Triage by UX team; not engineering.
Encourage subjective reports
'Felt weird' is a valid UX bug report. Bug bash demands repro; UX bash accepts perception.
Synthesize at the end
UX bash findings might point at bug bash candidates. Cross-pollinate.
“UX and bug are sibling concerns. Treat them separately; learn from each.”
If your team only does bug bashes, UX bashes are a multiplier. Different signal; complementary value.