Not just probably scared off some good talent, they had xoofx leave over disagreements with higher management. xoofx was one of their most senior devs, the guy who started the CoreCLR migration and was leading it.
They'll get there eventually, but the current roadmap says experimental CoreCLR in late 2026, which then in the best case means production ready in 2027. Unity isn't going anywhere, but at least as a dev who doesn't care about mobile (which is Unity's real market), competing engines have gotten much more attractive in the last couple years and that seems set to continue.
The funny thing about his resignation is that xoofx had a CoreCLR prototype already working around 2016-ish, but the company had "other priorities" and only took it seriously until recently.
The guy should just have been left alone and shielded from company bullshit to do the migration, or empowered to fight.
I know this is one sided but: Whoever from high-management lost this guy is an absolute loser waste of space who didn't do his job and will blame xoofx for “not fighting harder” or some other bullshit. Fuck companies, and fuck loser managers.