Why is 301 redirect not working on google?

Question

Google

Colleagues, good afternoon.
Our desktop and mobile versions were divided into 2 domains - doctu.ru and m.doctu.ru
First there was a move in May from http to https in Google - everything went ok, the pages in the index were replaced.
Then we decided to get rid of the m.doctu.ru subdomain - we made 301 redirects from all pages of the subdomain to the main domain. As a result, about 3 months have passed and traffic is still going to the mobile subdomain (with about 40% of traffic) and there are pages in the Google index, although according to the statistics of bypassing the robot, there has been silence since July.
Tell me, please, what are we doing wrong, why doesn’t the robot replace the pages of the mobile subdomain in the index with the pages of the main domain, taking into account 301 redirects?
PS Google did not "move the site" for the mobile subdomain - they just set up 301 redirects and that's it.

Answer 1

You missed a few steps from the instructions for transferring the mobile version back to the main domain.
You need to follow the steps:
1- From the new site, submit two Sitemap files containing the old and new URLs. This will help our crawlers detect redirects from old to new URLs and make porting easier.
2- Request a change of source site address to Searc... .