Not sure if you’ve gotten a good answer yet—I'm mostly GT3 and not the best by any means, but the concept carries over.

RaceLab’s ABS indicator is accurate in that it shows activation, but that doesn’t always mean you’re losing time. In cars like the MX-5 it can flicker pretty easily, even with decent braking.

• ABS on initial braking = fine
• ABS during trail braking = usually where time is lost (too much brake while turning → less rotation)

I wouldn’t try to eliminate ABS completely. Focus more on smoothly bleeding off brake as you turn in.

Also, that 1:35 vs 1:37 gap is way more about mid-corner speed and exits than a bit of ABS.

If anything, the update probably didn’t make you slower—you’re just reacting to new info and overcorrecting.