It also has to do with marketing imo. I think the pandemic messed up Yuehua's plans cause from my perspective they were trying to push them into the "western" Kpop market especially with the NA tour but due to the pandemic plans were cut and I guess they had to focus on Korea.
That said, Yuehua are horrible at marketing everglow. They only have Sihyeon being pushed as an MC in Kr while the others do nothing when they actually have Yiren who can be pushed in China. They are taking a big 4 approach with Everglow when they are a nugu level company in Korea even with all their resources. If EG were from any of the big 4, their approach would have easily worked with how solid (top 3 imo) their Discography is among 4th gen GGs and well rounded they are as a group.
It's so bizarre a group that arguably has 3 top tier level (Subjective) visuals in Sihyeon, Aisha and Yiren; two Ace level talents in E:U and Mia can't even utilize that to their advantage. Also they need to make a decision and start pushing them fully in either one of China, KR or the "West" (start with those generic YouTube channels every Kpop idol goes to when promoting to the English market) or all three.
Anyway I think it mainly is caused by the marketing and promotion of EG. If you aren't from the Big 4, you have to take the approach of carving out a niche market (monsta x & dream catcher), pushing members through variety content to get the Korean gp to follow (OMG, StayC) or going viral (Brave girls, Loona with the meme virality). Ofcourse there are cases of groups breaking through solely based on their music ((G)-Idle, Mamamoo(?)) but they still put in the effort to maintain it through promotions and marketing.