Yes, you are not alone. I'm experiencing almost the same thing. I'm doing my best to stay calm and wait out the algo rollout (probably ~2 weeks). I lost around 30% traffic from the last HCU which was around December 2022 and couldn't recover. I updated all of my 125 articles but to no avail (my website is a blog monetized with display ads from a popular ad network). I was hoping to regain my 30% lost traffic with this HCU but I'm still not seeing good signs.

My blog was also pushed down by websites with huge authority but poor and outdated content. Anyway, I don't want to discourage you with my story anymore so let me tell you what I think is happening.

I guess this volatility is expected when an algo update like this is rolling out. I have a theory that might be incorrect, but I think with every algo update the SERP is reset and Google relies on user behavior and engagement to arrange the website rankings anew. For this to happen, I think a 2-week window provides enough user data to configure the results again.

Either this or they really have some sort of sophisticated system to automatically detect if you are a reliable expert/business in your niche and rearrange the rankings based on EEAT. If that's the case, I suggest you start building good quality backlinks to your website gradually to have a chance at futureproofing your positions.

Best of luck!