Unreadable Color for markdown code block

[mat-m]

• [] Which editor/software are you using? VSCode 1.47.2
• [] Which theme are you using? Frontier from rainglow
• [] Have you tested the issue with other themes? freshcut, isotope, kimbie dark from rainglow, One Monokai Theme from Joshua Azemoh
• [] Which version of Rainglow do you have installed? 1.5.2
• [] Can you provide screenshots to highlight the issue?

With rainglow

freshcut and isotope also have the issue, not kimbie dark.

With One Monokai