If I’m not mistaken, lemmyverse.net did not always report properly from lemmy.world and there is a community with slightly more subscribers (https://lemmy.world/c/technology with 49.8k subs today)

where did my password leak!?

It was my understanding from years ago. If it changed in between, I stand corrected.

Actually, it seems like engagement is through any kind of interaction, commenting, upvoting, even downvoting, are used to boost a video visibility, because, as you say, their ultimate goal is maximizing money from ads.

OP is right to support creators via comments.

Note also that YouTube has automatic filters for comments, which will remain visible for its author only, but the creator can also shadowban someone from their channel.

Which viable alternative could work to mitigate ddos?

Out of my head, I think OVH offers such a service (but without free tier).