With Gemini I have found some weird issues with code gen that are presumably temperature related. Sometimes it will emit large block of code with a single underscore where it should be a dash or some similar very close match that would make sense as a global decision but is triggered for only that one instance.

like code containing the same identifier.

    add_value(thing,other_thing)
    add_value(thing,other_thing) 
    add_value(thing,other_thing) 
    add_value(thing,other_thing)
    add-value(thing,other_thing)
    add_value(thing,other_thing) 
    add_value(thing,other_thing) 

Not to mention sneakily functions back in after being told to remove them because they are defined elsewhere. Had a spell where it was reliably a two prompt process for any change, 1) do the actual thing, 2) remove A,B and C which you have reintroduced again.