Yeah, that's happening for me, too, lol. They had really similar numbers for a while, but I've seen them differ by quite a lot for the last month or two... Maybe YouTube is trying to consolidate to the new studio and running into trouble based on what sub numbers to look at?? I dunno... I wouldn't get too caught up in the subscriber numbers unless there's a really big negative reaction to a video. I think of subscriber numbers as a vanity statistic -- watchtime seems to be the statistic that matters the most on YouTube atm...
WOOOW Finally someone who thinks the same way I do! Yes, I totally agree with you.
Apart from getting some perks/benefits, the number of subscribers is just a vanity number at this point. The algorithm doesn't take it into account, YouTube doesn't care about your channel to be honest. They only focus on 2 stats when you upload a video. As you explained, and allow me to complement your answer, Watchtime/AR and CTR are the two most important stats at the moment. A recent study actually showed that YouTube is recommending longer videos.
** There's also a weird trend where YouTube is recommending OLD videos or 90-180 days old videos for some reason. I see this has happened to users in this forum including me. YouTube recommended a 90 days old video that went from 10K views to 100K views in a week, so don't lose hope in your old videos and always improve the thumbnail if you can!
Here are the benefits I was talking about until 100.000 subs, please let me know if I'm missing one (or if I made a mistake) and consider I'm not including the benefits YouTube gives in the YouTube Creators webpage
100 - Custom URL
1000 - Monetisation Review + 4K hours
2000 - I believe they will enable the Community Tab but not sure if this is meant to be for everyone in the future at 1k subs
5000 - Access to FameBit
10000 - Merch with Teespring that will appear in your videos
30000 - Join Button to accept Memberships
100000 - Silver Play Button and Personalised designs from Teespring