I'm not 100% confident in the artist tag. On one hand, I do know Zmeinir was the one who drew the thermometer asset, as confirmed by this tweet. As for the chibi Yuy, I'm not so sure. Zmeinir has drawn plenty of art for her in the past, including her current VTuber model, but I can't confirm that this specific drawing of her was made by them. It's been used in the thumbnails of at least two videos on Yuy's YouTube channel, but neither one credits the thumbnail artist in the description.