I can't really speak too deeply to this latest COVID research as it's out of my wheelhouse. Yes, it's "cultured microglial cells" but it turns out they're pretty important to your brain.

https://www.frontiersin.org/articles/10.3389/fimmu.2023.1158460/abstract

Here's a pretty decent look at what this might impact.

https://www.frontiersin.org/articles/10.3389/fneur.2021.654850/full