Here is a picture i found online with similar impact attributed to wind.
https://www.dreamstime.com/rice-fields-damaged-winds-image200409799
there are some others if you browse. Heavy rain plus the down draft could easily do it to a grain heavy stalk. I have seen similar in the US midwest when storms rolled over a field with ripe winter wheat close to harvest.
>> lkely you have either 1) air bubbles, and/or 2) dust/dirt / sanding debris from between coats. You will have to sand it out again lightly and recoat. You may have to take it back to bare wood if really bad.