Interesting argument. While iron before gold would be consistent, light before heavy also feels correct.
Never noticed that the issue was over chunk boarders, but I can say that I too have this issue. Thought it was just me though because it doesn't start as soon as the world is loaded, but instead after a few minutes. Can confirm I had no issues in 21w14a either.
What do you mean? Tinted glass is different from every other type of glass because it doesn't let any light through. That is its function.