yep, last-modified is there now but you’re not returning HTTP 304 not modified on a conditional request:
[13:13:41/19351] last unconditional update request: 2019-11-13 13:13:36
[13:13:41/19351] not using CURL due to open_basedir restrictions
[13:13:41/19351] stored last modified for conditional request: Tue, 12 Nov 2019 22:07:09 GMT
[13:13:41/19351] fetching [https://usa.newonnetflix.info/feed] (force_refetch: )...
[13:13:41/19351] fetch done.
[13:13:41/19351] source last modified: Tue, 12 Nov 2019 22:07:09 GMT
the transcript should look like this instead:
[13:14:38/20146] start
[13:14:38/20146] local cache will not be used for this feed
[13:14:38/20146] last unconditional update request: 2019-11-13 07:57:56
[13:14:38/20146] not using CURL due to open_basedir restrictions
[13:14:38/20146] stored last modified for conditional request: Thu, 15 Aug 2019 11:07:30 GMT
[13:14:38/20146] fetching [https://fakecake.org/testfeeds/random.xml] (force_refetch: )...
[13:14:38/20146] fetch done.
[13:14:38/20146] source last modified: Thu, 15 Aug 2019 11:07:30 GMT
[13:14:38/20146] unable to fetch: HTTP/1.1 304 Not Modified [304]
[13:14:38/20146] source claims data not modified, nothing to do.
by the way, i’ve just run your feed manually again and there was one new (or updated) item:
[13:11:52/18280] start
[13:11:53/18280] local cache will not be used for this feed
...
[13:11:53/18280] processing articles...
[13:11:53/18280] guid 2,https://usa.newonnetflix.info/info/81034946 / SHA1:429215afba4703cb273af127ef31d3b8f95be216
[13:11:53/18280] orig date: 1573596429
[13:11:53/18280] title 13th Nov: Maradona in Mexico (2020), Limited Series [TV-MA] (6/10)
[13:11:54/18280] link https://usa.newonnetflix.info/info/81034946
[13:11:54/18280] language en
[13:11:54/18280] author
[13:11:54/18280] looking for tags...
[13:11:54/18280] tags found:
[13:11:54/18280] done collecting data.
[13:11:54/18280] article hash: 22c03ba0648e517b7778b90d1a4c035558a0fb30 [stored=]
[13:11:54/18280] hash differs, applying plugin filters:
[13:11:54/18280] ... Af_Comics
[13:11:54/18280] === 0.0000 (sec)
[13:11:54/18280] ... Af_GoodShowSir
[13:11:54/18280] === 0.0003 (sec)
[13:11:54/18280] ... Af_Psql_Trgm
[13:11:54/18280] === 0.0011 (sec)
[13:11:54/18280] ... Af_Readability
[13:11:54/18280] === 0.0000 (sec)
[13:11:54/18280] ... Af_RedditImgur
[13:11:54/18280] === 0.0000 (sec)
[13:11:54/18280] ... Af_Tumblr_1280
[13:11:54/18280] === 0.0000 (sec)
[13:11:54/18280] ... Auto_Assign_Labels
[13:11:54/18280] === 0.0016 (sec)
[13:11:54/18280] ... Af_Img_Phash
[13:11:54/18280] === 0.0000 (sec)
[13:11:54/18280] ... Af_Video_Fill_Poster
[13:11:54/18280] === 0.0002 (sec)
[13:11:54/18280] plugin data: af_comics,af_goodshowsir,af_psql_trgm,af_readability,af_redditimgur,af_tumblr_1280,auto_assign_labels,af_img_phash,af_video_fill_poster,
[13:11:54/18280] date 1573596429 [2019/11/12 22:07:09]
[13:11:54/18280] num_comments: 0
[13:11:54/18280] force catchup:
[13:11:54/18280] base guid [2,https://usa.newonnetflix.info/info/81034946 or SHA1:429215afba4703cb273af127ef31d3b8f95be216] not found, creating...
[13:11:54/18280] base guid found, checking for user record
[13:11:54/18280] initial score: 0 [including plugin modifier: 0]
[13:11:54/18280] user record not found, creating...
[13:11:54/18280] resulting RID: 9952107, IID: 6596795
[13:11:54/18280] article updated, but we're forbidden to mark it unread.
[13:11:54/18280] assigning labels [other]...
[13:11:54/18280] assigning labels [filters]...
[13:11:54/18280] looking for enclosures...
[13:11:54/18280] article processed
[13:11:54/18280] guid 2,https://usa.newonnetflix.info/info/81078466 / SHA1:8c2c97526f4c5cd17b27b6ef9d1a1a5b398cdcd8
[13:11:54/18280] orig date: 1573520829
[13:11:54/18280] title 12th Nov: Jeff Garlin: Our Man In Chicago (2019), 58m [TV-MA] (6/10)
[13:11:54/18280] link https://usa.newonnetflix.info/info/81078466
[13:11:54/18280] language en
[13:11:54/18280] author
[13:11:54/18280] looking for tags...
[13:11:54/18280] tags found:
[13:11:54/18280] done collecting data.
[13:11:54/18280] article hash: ef23215fddee52f6045b878eab54ed7627c4c435 [stored=ef23215fddee52f6045b878eab54ed7627c4c435]
[13:11:54/18280] stored article seems up to date [IID: 9951104], updating timestamp only
[13:11:54/18280] guid 2,https://usa.newonnetflix.info/info/80178941 / SHA1:c307fd8089b0314282140a649d57caeed532ba2d
[13:11:54/18280] orig date: 1573506551
[13:11:54/18280] title 12th Nov: Harvey Girls Forever! (2019), 3 Seasons [TV-Y7] - New Episodes (6.35/10)
[13:11:54/18280] link https://usa.newonnetflix.info/info/80178941
[13:11:54/18280] language en
[13:11:54/18280] author
[13:11:54/18280] looking for tags...
[13:11:54/18280] tags found:
[13:11:54/18280] done collecting data.
[13:11:54/18280] article hash: db7a7edf7f33cc4b075356b9b05c3b70209ed633 [stored=db7a7edf7f33cc4b075356b9b05c3b70209ed633]
[13:11:54/18280] stored article seems up to date [IID: 9951105], updating timestamp only
[13:11:54/18280] guid 2,https://usa.newonnetflix.info/info/81070963 / SHA1:1ecac424811f3af42cba53aa2c62fe69f68b005f
[13:11:54/18280] orig date: 1573456151
[13:11:54/18280] title 11th Nov: Chief of Staff (2019), 2 Seasons [TV-14] - New Episodes (6.95/10)
[13:11:54/18280] link https://usa.newonnetflix.info/info/81070963
[13:11:54/18280] language en
[13:11:54/18280] author
[13:11:54/18280] looking for tags...
[13:11:54/18280] tags found:
[13:11:54/18280] done collecting data.
[13:11:54/18280] article hash: d64547edb5e3011415f788cc6b18d8aed9110ebb [stored=d64547edb5e3011415f788cc6b18d8aed9110ebb]
[13:11:54/18280] stored article seems up to date [IID: 9951106], updating timestamp only
...
as you can see, plugins like Readability are only applied to the new item, everything else is skipped. so it looks like your feed is working properly.