Nope, there's no fan service. In fact theres only a love triangle with the priestess, the MC, and the Mc's lover.
And I agree, I was also gonna drop it because the addition of the cat girl but as I read I saw the line drawn between the cat girl and MC. The relationship are well though out and understood easily by the readers, so no misdirection on the relationships.
The cat girl made it pretty fanservicey I dropped it when she appeared (I also hated the outfit switch for the priestress)
https://www.mangago.me/read-manga/isekai_shikkaku/nbt/mpn_chapter-2160186/pg-4/
It was the comments that made me give it one more chance since people said it was actually not that bad
And yeah agreed with the love triangle, thankfully it doesnt feel like a harem
Ok this is hilarious, I was about to drop it cause of the fanservice but it gets better & I enjoy the dark humor