Drop in positions after connecting an SSL certificate? Can it happen? How to overcome?

Question

Google

We want to connect an SSL certificate to an online store.
Age - 3 years.
In Yandex for the right queries - in the top.
There is an opinion about a potential problem:

But if the site is already operating and you suddenly decide to switch to ssl, then be prepared that Yandex will be stupid for about half a year, until it realizes that the site is completely on SSL. Checked.

Source - talk.pr-cy.ru/topic/20147-ssl-sertifikat/...
Tell me , please,
is it really possible to avoid this problem?
And does it exist at all?

Answer 1

Yes, it's impossible to avoid.
Even if you do everything right, write all the redirects, rules, robots.txt, etc., then in order to move to https and you would not have duplicates in the index - you will have to throw out everything that you currently have indexed by http from index and re-drive via https.

Answer 2

Yes, there will be a temporary drop.