I've been working on a large-ish Blazor (Server) application for about a year. The choice to use Blazor was not mine, but I went into it with an open mind. For context, I have used React and Angular in the past.
I will never used Blazor again.
Performance is not good, with CPU always at some base level, even when idle. My machines fan is always cranking while developing it. Hot reload does not work consistently (on like 25% of the time), and when it does, it is slow, so it might as well not work at all. Everything in Blazor just feels half-baked.
I'm old enough to remember things like "ActiveX Documents" and Silverlight, where were other attempts by Microsoft to provide a way for people not to have to learn and use a proper front end framework, and I think Blazor will end up on the scrap heap with them.
Microsoft has a bad habit of touting the next big thing for developers to use and then abandoning it several years later. This feels like that to me.