Thanks for giving all the details so we can try to help!
Based on your answers, my best advice at this point to try to revive/improve it...
1. Verify that all 3 green checkmarks are there on your channels feauture eligibility, if not verify the account further.
2. Take any links out of bio and new vids descriptions or even old vids if there are not a ton of them.
3. Increase vid drop rate to 1 vid every 2 days. This is for a few reasons.
4. Make sure next vids are leaning toward more innocent side, less YMYL emphasis if there is any. For example tone down what is comtroversial, and make more positive/best practice.
5. Interact slowly bit by bit more with community, other vids in niche, comments, likes, etc.
6. Get some new traffic there by funneling from your other legit sources like other social media or embed in website. Try to cross-promote or get shoutout from others, email creators. Go old-school organic and take control like it was day 1.
7. Make post/poll on account, if you dont already add a comment pinned to top of each new video, then start.
8. Optimize titles, descriptions, hashtags, keywords, file titles and meta, contact info in descriotion, disclaimers if needed, intro, outro, anything else to freshen up.
9. Really be hard on yourself to improve and appear to be more legit, whitehat, out to help others and not gain for yourself through links, more interesting, more engaged with community and asset to YT, and concerned about their safety and wellbeing and security etc, and give them all the reasons to start promoting your content again.
10. Im tired and busy, cant spend more than 5 min on this comment, I barely remember what the question was now, bye!
Good luck, hope this helps someone!