How to find out what caused the traffic drop from search engines?

Question

Search Engine Optimization

At the beginning of July I launched a new version of the site (this is a small regional information site, 130-150 thousand visits per month). Exactly from that moment, traffic from the yandex and mail.ru search engines fell by about 20% and has not risen to its former levels to this day. Traffic from Google hasn't changed.

The fall goes evenly across all sections of the site.
In addition to the fact that a new version was launched, the hosting was changed and HTTPS was added. (With a forced redirect)
As I understand it, traffic could be affected by 3 reasons:

1. new layout
   
2. change ip address
   
3. HTTPS
   

Which one do you think contributed to the fall? How can you find out? Are there other options?
PS
For 10-20% of the pages, the address has changed, from this type of "/news/page_500/" to this "/news/500", but in this section, the 301 redirect works from the old format to the new one.

Answer 1

I think layout, ip is not important at all. We have to wait, in time everything should be restored ...