My domain registar said that they cannot set a CAA record. It can be a co-cause? I read that post and it seems a “temporary issue” of .ru domains. Am I wrong?
It also seems that I cannot do anything If not “wait”. Am I wrong?
No, there is no need to add a CAA record only that your DNS servers answer correctly saying ok, you are requesting a CAA record but I've no info, that is ok. I've checked your domain and it is not your fault.
Yes, seems it is temporary.
Correct, it is not your fault and you can do nothing to solve it... just wait.