@123Toid – I think part of the issue is what a person is looking for at that period in time. If I may, before audio, I’ve been into computers and building computers for years. I do watch a lot of reviews of newly released hardware. But, the frequency with which I fully watch the reviews will depend, in part, on new features being introduced, my needs for purchasing or upgrading equipment, emergent trends in the space, etc. This is how I balance my interests.
The smaller tech channels I watch, like Hardware Unboxed, do some of the most in-depth reviews of computer monitors. But since I use a 50″ 4K TV as a monitor, I do not watch those reviews as often, although I would not hesitate if a person down the road is looking into buying a display to send them there (and to rtings.com).
In the same way, although I did watch this review, I am not nearly as interested in headphone amps. Now, that is a personal thing, and I cannot speak to the rest of this community and your YouTube followers on what their interests and needs are. But that may be the case with some of the review videos.
If others are like me, even if it is a review I would be interested in, I do find myself with limited time at times and hobby viewing takes a backseat in those cases. The Acrylic video is an example of that. I started watching, but never finished it and never swung back around. Because, although I am interested in the content, I got busy and just didn’t finish it (note: it may have even finished playing but I got busy in the morning and just didn’t pay attention or was out of the room for the conclusions).
Also, in recent times, it seems YouTube’s algorithms for finding new content has… changed. Most notable in the YouTube news segment, I have seen discovery recommendations when not logged in change over the past few years (but that has to do with discovery and growth; not on interest of subscribers). YouTube is effecting ways people organically find what they are looking for. I do not know if this has effected your channel or not (one way to check is seeing if there was a point at which discovery of your videos by non-subscribers has a precipitous drop off at some point, after which it remains lower than the higher historic levels). If that is seen, then that correlates to an algorithm change by YouTube. Considering your videos are apolitical, you shouldn’t be effected, but that might be worth looking at.
Another reason could be (and this is only if historic data is not the same as current data on performance of this type of review video) that in the US, there is an economic situation going on where 4.3M quit their job in August alone, with more in September to be discussed (it seems they started tracking quitting jobs in 2020, and it seems that the release of that information is lagging by 1 month as compared to the prior month’s jobs numbers, released the first Friday of the first full week of the subsequent month by the Bureau of Labor and Statistics, so the narrative will be seen in the coming months). Because of that, there could just be the case people are not, at this moment, interested in hearing about products due to their own finances, or supply issues may make obtaining certain products harder, as putting in time restrictions (such as ports being cut back to 8 hours a day monday through friday for C restrictions has caused the backlog of delivering goods, with the Treasury Department ominously saying that we will not go back to normal hours until everyone takes a shot, not trying to get political here, just trying to report what US officials are saying).
So, it is hard to say, but hope something I said in this post might help.