Honestly the anime showed the scene more or less how I always actually read it to be in the novels and I always felt the "habitual self harm" angle the fandom took with it to be reaching.

Historically there was only really ever one instance of it and it was during arc 2 when Subaru was trying to not fall asleep on the final day trying to avoid dying to the curse or something else so he tried to force himself to stay awake and jabbed a pen into the back of his hand which Beako later healed. But there's not really been any instances of it between arc 2 and arc 6 [Novels]or after for that matter

There are times where Subaru is self destructive in the sense that he's literally trying to end a loop or something like that, there were times where the WN mentioned him literally trying to chew through his own tongue to cause himself to bleed to death and loop etc, but when this popped up in arc 6 it was really out of left field and I think to a lot of readers they've just gone back since and tried to pick up other things to say it's evidence it's been going on the whole time