No it’s not a red flag. I do high end content, or at least have a go at few savage / extreme clears every expansion as I’m not someone who would enjoy something like a raid schedule (I personally dislike subjecting my gameplay to a schedule, it’s a pastime for me and a static schedule would make it feel like a chore), and I never had problems clearing without looking up people on FF logs. I have my own character opted out for harassment reasons I encountered back in WoW, where the player base was overly toxic by standard and I’d also say by design. From my 10+ years of experience from WoW, I absolutely agree with Yoshi that DPS meters and logs do fuel toxicity and are unnecessary unless someone wants to optimise their gameplay to the limit.
From my experience with Savage / Extreme, the only reason when logs might be needed is when forming a static and you as a group want to min-max and optimise the **** out of the gameplay / rotation.
Otherwise, I have never felt the need to consult FF logs in any content I have cleared, because in 99% cases of clearing / progging through Party Finder, it is very evident what is the issue if the group is struggling, and people who screw something up usually identify the problem on their own. Plus most PF parties disband before any issue might be resolved, but that’s another topic entirely.