TLDR
Fromis is the least popular group at Hybe, selling under 200,000 albums. After moving to Pledis, they surpassing 100k in sales, but slowed down after losing a member. Other Hybe groups except BND (500k) sell over 1 million albums and even Nuest sold 200k before disbanding.
My theory is that Hybe likely kept Fromis, thinking 100k sales were huge enough for a gg. They weren't experienced with gg and even popular group like Gfriend didn't reach that. Mind you, in 2021, Itzy and Red Velvet sold around 200k-300k albums in the first month, which obviously 100k is quite a big deal for a new company with no experience like Hybe. For Nuest unfortunately, all Hybe bg were hitting 1 million sales at that time which the gap was really huge.
In 2022, Fromis had comebacks in January and June. Newjeans hadn't debuted, and Le Sserafim faced a scandal. Hybe might have felt pressure to re-sign Fromis, perhaps as a backup. We know Hybe doubted Newjeans' success, and Lessera is still fighting for Garam.
Fromis took a one year hiatus and only one cb this year right after the success of Hybe new gg. I understand they lost a member and face some minor controversy, but not like it's new in Kpop. The company obviously pay less attention to the group now and didn't want to invest much in them. Luckily, Fromis renewed their contract last year before Hybe gg explode in popularity; otherwise, they might have faced a fate like Gfriend especially as Pledis will debuting new gg soon too.