Everything about your post is slightly indicative to me of javascript failing, for some reason.
So many actions taken, upvoting / boosting / replying, do javascript actions. However, all of these things have fallbacks in the case either: javascript hasn't fully finished loading on the page yet or javascript requests failed.
As I said this is true for all other actions, so when you vote or boost there are also http GET routes that handle those requests.
It's hard for me to guess more than that, it could be the JS is loading a bit slow and you click before the page finishes loading, or it could be a different error like maybe the request fails. There might also be something else involved, I'd have to double check but mercure might involve itself in dynamic page updating as well... Do you happen to notice if pages are still loading when you take actions, or in fact just browse with javascript disabled? There's also that, last I checked, all the JS files had defer on them so don't block page loads, which is what makes this more likely to happen. Whether that's good or not, I can't say, it's been like that since I first looked but might require more research to know whether it can be split between JS that should block page load and JS that can be deferred