My rough rule is it’s OK to ask once politely.
If you aren’t feeling right about the comp, it’s generally better for your prospective employer to know now.
Bring it up politely, explain your reasoning. If the reasoning makes sense, and the overall comp is within expected range, they may say fine.
And be OK if you get a No back, politely explained as well.
The bigger the company, the less well this works.
