Been using Boostnote for the last few years. Boostnote's great, but it doesn't have note nesting / trees, so I figured I'd give Trilium a shot.

Downloaded Trilium, tried to type in a standard GFM Markdown fenced code block with a language identifier for syntax highlighting, and it kept converting it to a "Plain Text" block as soon as I typed the third backtick, making it unusable.

That's a hard blocker for me. I write Markdown all the time, and I don't want a pseudo-WYSIWYG editor mangling the Markdown I'm writing as I type it. I also need to be able to add code blocks, with highlighting, at any point in the middle of the notes I'm writing.