Cookie “mangadex_session” will be soon rejected because it has the “sameSite” attribute set to “none” or an invalid value, without the “secure” attribute. To know more about the “sameSite“ attribute, read https://developer.mozilla.org/docs/Web/HTTP/Headers/Set-Cookie/SameSite
Actually, I have had that issue occur a few times as well past couple of days. I would read a chapter and it would not be marked as read when I would go to my follows page or the manga's homepage. Definitely now messing around with my cookie setting or whatnot. Thought maybe there was possible desyncing going on, but can't be certain since they did put in that nice new monster server.
How about providing some additional details, as it appears the issue only impacts a small amount of users. A lack of information makes reproducing/troubleshooting/fixing the problem you are having difficult for devs.
Platform/Device:
OS and Version:
Browser and version:
Browser extensions/add-ons:
Have you tried clearing cache/cookies/storage?:
Are you using private/incognito mode?:
Does your browser clear/cleanup data when closed?:
Does this happen when using another browser and/or with a clean browser profile?:
And just for reference MD does store reader settings in 'local storage'