Checked the authors website; watermark made searching for it easy. They have been using this consistent art style since 2021. They have been posting art to Twitter since 2011.
Don’t know what in this comic you could possibly see as a give away for AI use.
Your info is a bit out of date. Epic already sold off Bandcamp back in 2023 during layoffs. Its owned by Songtradr now, who I personally know nothing about.