Why is MacOS Ventura making my 2020 intel macbook air run so slowly?

Noticed many lags too. My Macbook Air (2019) - 8 GB RAM even crashes frequently with kernel panic errors, sometimes directly after I boot, then it won’t turn on for several minutes. When I’m finally able to login I am welcomed by black screens / freezes / mosaics, sometimes faster, sometimes after ~30 minutes. All of that started after I upgraded from Big Sur to Monterey. Hoped to fix it with upgrading to Ventura, since 2019 Macbook Airs are officially supported but it didn’t help. It got even worse. Now I’m trying to downgrade back to Big Sur and I’m confident it will fix my issues. I suspect Apple is intentionally making the new macOS’s more resource intensive so that older devices slow down or stop working altogether. I think they're also purposely not optimizing anything for Intel processors anymore to get people to buy a new M1 or M2 Mac. If my suspicions prove correct and the problems no longer occur under Big Sur, indicating that this is not a hardware but software issue, this will be my last Mac. The release of Monterey was 1 year ago, and thus I expect the operating system to still run stably on a device from 2019.

Wish you good luck with the downgrade, I have no hopes that Apple will patch the problems. Monterey will probably be the last macOS for you. And I don't think I would miss my Mac either.