In early startups specially in b2b, product designers are not designers they're rather design support. Always restricted to reach till minimum viable ux.
Though whatever gets shipped at the end is better from past but power of shaping product is largely placed at PM's table and engeneering table (feasibility).
Now you can avoid complaing and show high agency, partner with PM in defining Product but the default power house is still PM, not the designer. Also you don't have time for this because designs need to shipped to add to next sprint.
At the end you just take a deep breath and sigh because you made something better, bit better if not far from what existed before.
I guess high impact/ product definition work gets done by designer in big orgs only not only early age startups.