The effect has been considered, carefully, by a variety of researchers, and to date the majority of them have found no reason to believe there'd be more than the most negligible of effects on ecosystems. (When specifically eradicating the species that spread disease to humans.)

https://www.nature.com/news/2010/100721/full/466432a.html

https://www.bbc.com/news/magazine-35408835

https://www.smithsonianmag.com/innovation/kill-all-mosquitos...

https://outline.com/428REE

https://www.npr.org/sections/goatsandsoda/2016/02/20/4670944...

You can find some articles from researchers in the field that are concerned about removing them (https://phys.org/news/2017-07-mosquitoes.html), but those researchers don't seem to have done as much work in the role of individual mosquito species in their environments.