Speaking as someone who has known her since before she had any reviews, I can say she was never comfortable with the review system/rankings in general and always wondered if getting to be the top 10 list was a good thing or not. And she has been less available of late.
she's on TER but gone from the rankings......
for Hobbyists to be excluded from the top 100 posters. I wonder if there is the same for Providers and the top 100 rankings and what benefit would there be to that exclusion
My guess: she has not been reviewed in long enough to have her scores be counted as "active".
I bet a new review comes in soon and that we will see her name atop the list once more 
Speaking as someone who has known her since before she had any reviews, I can say she was never comfortable with the review system/rankings in general and always wondered if getting to be the top 10 list was a good thing or not. And she has been less available of late.
Her last review was 6 months ago. No mystery here.
If she gets a new review her name will pop back up on the list
To be honest we get comfortable with our regulars & not everyone writes reviews. I know my twin & I were dropped from the top 100 list awhile back due to the guidelines. TER requires providers to be active in the community & need a review every 6 months to be on the list. Easy to fade away when your no longer on top.