I'm not sure which one are you talking about, but here's my take about it:

1. It might be a bit controversial take, but for our fansub release, we do have an out-of-bound/"invisible" (pos at 1920x1080, or utilizing iclip) subtitle line that should visible and warns people who used unsupported players or even fanstream sites that don't do hardsub (especially for HiA.... site).

We're cool for any fanstream that do hardsubbing because we don't want to hear people getting mad over broken typesetting just because their player doesn't support ASS nicely, or even got converted to SRT. We got this complains over and over from that particular site, so we did this extreme measure. For this particular episode, we didn't put that since no heavy typesetting has been added.

2. For the thing you saw on the top left of the video on this episode is a credit of the team who worked on it. I don't consider it as watermark as you can easily remove it from your subtitle editor and it's pretty much one cut length, but morally speaking, it's better to leave it for attribution. (and Nyaa doesn't have the clause related to it, so yeah)

3. And if you're talking about the previews on the entry page.... it's a watermark for the preview itself, not actual video. I added it so I can troubleshoot wtf happened with my previewer script kek XD

They only marked the screenshots on nyaa. If they watermarked the episode, they would have shown up in the screenshots here on AT.

Maybe do a little research before making idiotic claims next time.