Your comment was deleted because we generally discourage comments regarding up/downvotes - see the examples in the Help Center article on the commenting privilege:
When shouldn't I comment?
Comments are not recommended for any of the following:
- Compliments which do not add new information ("+1, great answer!"); instead, upvote it and pay it forward;
- Discussion of community behavior or site policies; please use meta instead.
Your comment, "If a question gets three answers from high reputation users then it certainly do not deserve downvote." seems to me to fit into these categories.
I don't think it's fair to say that your comments are repeatedly deleted - you have only had two comments removed this year, the other being removed as 'no longer needed' after the changes you suggested to a post were made.
If you see comments from other users which you'd like us to take a look at, you can flag them for our attention.
Regarding your deleted question, "What possible legal action a country will face if it's proved that a leaked biological material from it caused millions of deaths worldwide?", this question was deleted by three community members after being closed - also by community votes. The close reason was as follows:
Questions asking for the internal motivations of people, how specific
individuals would behave in hypothetical situations or predictions for
future events are off-topic, because answers would be based on
speculation and their correctness could not be verified with sources
available to the public.
I don't see a need to overrule the community's decision in this case, but if other members with the moderator tools privilege disagree, they can cast undelete votes to restore your question.
I appreciate it can be frustrating when your content is deleted without explanation, so hopefully this helps you understand why your content was curated in this instance.