Small g:markdown_minlines truncates set of <backtick>s (such as <backtick> class s{~s();} <backtick> text <backtick> class x{~x();} <backtick> to class s{~s();} <backtick> text <backtick> class x{~x();}, which has _strikethrough_ of s();} <backtick> text <backtick> class x{)

[SwuduSusuwu]

Was told that this ( vim/vim#15406 ) is not an explicit problem with Vim's core, but with Vim's Markdown module.

The problem with sin sync fromstart or g:markdown_minlines 6666 (other than performance) is that this is just a local fix (does not suit open source projects which you contribute to).

[SwuduSusuwu]

The problem is that the minlines window is small (which clips off the top of the block) to process the scripts fast, but Markdown must use the context of <backticks> which exists past this window.
Proposed fix: do not process Markdown across <backtick>s;
<backtick> (which begins or closes a code block) should have Markdown stop;
Thus <backtick> class s{~s();} <backtick> text <backtick> class x{~x();} <backtick> /
class s{~s();} <backtick> text <backtick> class x{~x();}
must both have the ~ ignored (as the ~ crosses <backtick>s).
If you do this, all sizes of minlines can process truth.

[SwuduSusuwu]

Proposed fix 2: post-/: if(1 & context_symbols['<backtick>'].size()) { execute("sin sync fromstart" /* or "let g:markdown_minlines 6666" */); }

The rest of vim's languages/syntaxes should have such fixes;
Proposed fix 2 is generalizable to: for(auto symbol : context_symbols) {if(1 & symbol.size()) { execute("sin sync fromstart" /* or "let g:markdown_minlines 6666" */); return; }}