> invalid DMCA takedowns do open you up to lawsuits

Invalid takedowns don’t open you up to anything. The only risk to takedowns is misrepresenting the purported owner but that’s not the case here and the risk would be from Funko not Itch.

Much of the reason for DMCA abuse is that beyond the notice being assumed legitimate there is basically no risk to the complaining party until they dispute a counter-notification.

Not that this is relevant in this case, as it was not a DMCA takedown. A takedown notice would have been addressed to Itch.