High CTR but low impressions - why does YouTube not show video?

My channel's first video ever (posted less than 2 months ago) has way higher CTR than any of my vids, yet is has way lower impressions than all of my other vids.

Some stats:

• 20% CTR average for last week
• 12% average CTR since posted
• 100% CTR for its first 24 hours
• Total only 1.9k impressions
• Most of the traffic has come from my channel page and sharing it on social media. Only 18% is from YouTube search and browse features
• It has 6 minutes avg. view time, total video runtime is less than 10 minutes.
• 100% upvotes

My last video (posted 5 days ago) already has 20k impressions and is doing fairly poorly with CTR (average 2.2%). Even my best video (800k impressions) only has 4.6% CTR.

What could be the reason for YouTube not showing this video to hardly anyone, if it far outperforms all of my other videos on every single metric? (CTR, upvotes, average view time) I can even see as impressions increase, CTR increases (which seems to debunk the theory that high CTR is only from small impression count).