This is a display glitch. The berry that appears is one that you fed to a previous wild Pokemon. For example, when I do a Registeel raid and catch it with a golden razzberry, the first wild Pokemon that I tap on immediately after the raid will appear with a golden razzberry (but will not be easier to catch).
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Wild berries
Sometimes I encounter a wild Pokemon where there's already one of the berry symbols in the top right corner, without me having given him anything.
However, what I noticed is that when a Pokemon automatically has the Pinap one and I catch it, I get no extra candy. So what is the significance of the wild berries? I tried giving a Pinap to a Pokemon supposedly already having a Pinap, thinking I would get increased effectiveness out of it,b ut it was the usal double amount.
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Answers
It's a visual glitch - the last berry you used to catch a Pokémon will show up on the current Pokémon. So if you used a Pinap to catch a wild Larvitar (you lucky trainer!), when you tap on the Pidgey next to it (why ignore the free 125 Stardust, amirite?), the Pidgey will show up with the Pinap symbol on it as if you used a Pinap on the Pidget.
