I assume that It is because of I have some postings generated by Gemini.
as much as I hate to say it, I don't think that google are bothered by AI content. Now, if it is BAD content, then yeah, it could be a problem no matter if it's AI or not
So I don't think that the AI content itself is the problem, as much as it's whether it's bad content...
This being said, there was a google update during that time (see link below), so it's possible that the reason for which you got traffic was because of that update, but normally you wouldn't have gotten traffic otherwise. I'm saying this because...
1) the period during which you got traffic is exactly the same period during which the update ran
2) during updates, random sites go up and down in rankings / traffic randomly
So, based on these 2 things it's possible that you've just been the lucky benefactor of google's updating algorithm, otherwise you might have not gotten any traffic (yet)...
https://status.search.google.com/products/rGHU1u87FJnkP6W2GwMi/history
So I shut down all the postings, and made it as 410(gone) responses.
well, this is not very smart. As far as I know there is no reward for domain age, but there is a reward for content age, and your 2 months content has lost its history if you've deleted it, which means that it might be harder to rank that content again in the future if you decide to bring it back.
This is not 100% certain, however, so bring it back again, re-create the sitemap, and re-submit it to GSC all over again (but only if the content is good, or after you improve it, otherwise - if it's been bad content to begin with - don't bother!). And don't delete aged content ever again (unless it's bad maybe, but even then, it's best to just improve it instead of deleting it)
Indexs are not gone, but in SERP, I can't find anything.
that's not bad. The fact that your content is still indexed it means that google finds it valuable enough to keep it in their index, which many sites can't pride themselves with
So yeah, bring that content back if it's not garbage, and try to rank it somehow (improve it, build links - both internal and external - to it, etc). By the way, from what I understood, ranking takes time nowadays, so the fact that you're not ranking within 2 months is not necessarily bad. People say that ranking can take 6 month or longer now, so yeah, don't take rushed and radical measures again, keep doing things slowly but consistently, abrupt measures are never good in SEO except for when you're in dire need to salvage a sinking ship, but even then I'm not sure they're worth it...
my guess is that the reason you've ranked is because of the December update, normally you shouldn't have ranked so soon to begin with...
since your site is still indexed (therefore google still trusts it), keep working on it as usual (publish content - slowly and gradually though, don't publish 100 posts a day or other retarded number like that - build links, improve CTR, UX and EEAT scores, etc... the usual stuff). And - after 1-2 months of such slow but gradual building up - I dare predict that your site will gain rankings and traffic...
Just my 2 cents, you can obviously wait for better advice if you want
