Is canonical required for a mobile site?

Question

Search Engine Optimization

A number of questions that have been tormenting me for more than a month.
I have one project that gets 50% traffic to the desktop version and 50% traffic to the mobile version.
There were no questions if it weren’t for one thing, but what’s on the mobile, what’s on the desktop version are different title and meta, plus the content itself is slightly different (just a little bit), this is due to requests, to make it clearer here is a very good example:
Desktop title (domain.com) => Wallpapers for PC
Mobile title (m.domain.com) => Phone pictures The
site is old and ranks very well in Yandex, but there is a problem with Google, perhaps precisely because there is no correct canonical
you need to do the following:
On the desktop version, place canonical

<link rel="alternate" media="only screen and (max-width: 640px)" href="https://m.domain.com/">

And on the mobile version 1. It turns out that if everything is done this way, then Yandex will consider the mobile version not canonical and requests will simply fly out? 2. Will I lose positions in Yandex for the mobile domain? 3. Is it necessary to specify additionally the canonical of the current page in the desktop version, i.e. Not this way
<link rel="canonical" href="https://domain.com/">

<link rel="alternate" media="only screen and (max-width: 640px)" href="https://m.domain.com/">

But like this?

<link rel="canonical" href="https://domain.com/">
<link rel="alternate" media="only screen and (max-width: 640px)" href="https://m.domain.com/">

Answer 1

close one of the versions of the
canonical from Google, you need to indicate if the pages can be accessed within the site,
if in fact they are not connected with you - this should not be