MRE:
from pixivpy3 import AppPixivAPI
ACCESS_TOKEN = "xxx"
REFRESH_TOKEN = "yyy"
client = AppPixivAPI()
client.set_auth(access_token=ACCESS_TOKEN, refresh_token=REFRESH_TOKEN)
# Tested on those 3
# illust_id = 125723831
# illust_id = 125478796
illust_id = 124297432
details = client.illust_detail(illust_id)
print(details) # OK
comments = client.illust_comments(illust_id)
print(comments) # <Response [404]>
MRE: