Seeking Advice: Sudden Ranking Drop, No Growth Despite Optimization, and Keyword Impression Crash

Hi everyone,
I'm currently managing two websites and recently encountered a few SEO issues that I haven't been able to solve. I’m hoping someone here with more experience can help shed some light on these problems.

Problem 1: Sudden ranking drop (without deindexing)
One of my websites used to rank #1 for its main target keyword, but suddenly the ranking disappeared. The page is still indexed — it’s just not showing up in search results anymore.


What’s strange is that for related terms, the page still ranks #1. For example:

• Brand + Entertainment City: ranking disappeared
• Brand + Entertainment: still #1

This also happened once before — the ranking came back after around two weeks, stayed for another two to three weeks, then disappeared again.
What could be causing this? Algorithm update? Temporary filter? Something else?

Problem 2: No ranking improvement despite proper optimization
The second site has been fully optimized:

• High-quality and unique content
• Strong internal linking
• Good backlinks
• Fast performance

Despite all of that, the rankings have shown no significant improvement. In fact, many competitor sites with much weaker content and structure are ranking higher.
What might I be doing wrong? What should I focus on if I want faster ranking growth?

Problem 3: Sudden drop in keyword impressions for both sites
Both websites used to appear for over 100 keywords. But around the end of February, that number dropped sharply to only 10–30 keywords, mostly branded queries.


This happened to both sites at the same time.
Is this likely to be the result of a Google update, indexing problem, or something else?

https://status.search.google.com/

Ranking Core Update in process.

Moreover-

• High-quality and unique content (This Is Subjective, One Man's Gold Is Another's Trash)
• Strong internal linking (Are You Sure??)
• Good backlinks (Again Subjective, are links from someone Google trusts? i.e high authority in the niche)
• Fast performance (GTMetrix and pagespeed.web.dev Passed?)

Plus the KW + City type of KW needs extra meticulous process to sustain consistent ranking. Like mentioning of the Country | City in the content, or if plausable dedicated pages for Local area target.
I may be wrong, I'm not pro but sudden impression drop clearly points to weak authority in the niche.

Google is evolving each milisecond, try to keep up, No one has the perfect answer, Evryone relies on 1. Good Research 2. Good Testing 3. Patience.


EDIT
While typing the answer, The core update was closed. So wait a week before gauging your rank losses.