Google warning " Indexed, though blocked by robots.txt"

Hello ,
I need your advise on this issue.
I just created the website last month, using shopify platform.
The robot.txt (can not modify) block google to access cart and checkouts.
Foe some reason google indexed these two urls, I have to de-indexed these two urls, but this is just a temporary solution.
Does this warning affect my SEO ranking?
What is the best solution to eliminate from warning in future.
Thanks for your expertise.

Don't worry this will don't affect rankings.

No, it doesn’t affect your rankings. However if you don’t want Google to index certain parts of your site, using robots.txt to block Googlebot is not recommended. Proper way is using noindex meta tag.

Its bug, they failed to fix it. Its going on from like 5 or 6 months. Correct me If I am wrong.

why you want to de-index. any specific reason?

Purush said:

why you want to de-index. any specific reason?

Click to expand...

Purush said:

why you want to de-index. any specific reason?

Click to expand...

Hi Purush,
The cart was already indexed, it conflicted with robus.txt which block cart url ==> trigger warnings from google.
De-index is working fine for couple months, later on the warnings come back.
it's advised that I should put non-index on this specific page, put it does not work.
Thanks