Having blots or marked with blots; stained or spotted (less common variant of blotchy).
From blot plus -y adjective-forming suffix, creating an alternative to the more common blotchy to describe something full of blots.
Blotty is the simpler, older form, while blotchy is the newer variant that became more popular—English often has multiple forms for the same idea, and sometimes the newer one wins out even though both are correct.
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