Had 100% same issue few months ago, here https://forum.maxthon.com/index.php?/topic/28976-maxthon-pc-7311701-beta/#comment-148692 is explanation but I dunno why it's happened just now for you, so maybe it's because of some other reasons.
Maybe it's connected to this old cloudflare issue https://pq.hosting/en/news/solutions-for-users-facing-ech-blocking-in-russia ?
I got working by installing https://github.com/Flowseal/zapret-discord-youtube/releases when ~1.5 month ago problem appeared.
I've reported it while ago and was fixed only when I've disabled hardware acceleration. It also fixed some other bugs like video crash while playing youtube and text distortion while scrolling or opening downloads list. But possible downside that RTX video wouldn't work anymore if it even was implemented there and much slower work with VR videos!
I'm using 4.9.4.200 portable. Tried to disable extentions (including Adblock) and Avast web screen, in all previous versions of Mx 2, 3 and 4 there were no such a bug (marked red color). I'm not using Mx account.
9353309 replied at 2014-11-8 19:24
В 4.4.3.1000 хреново работает качалка. На некоторых файлах ...
В 4.4.3.2000 воз и ныне там. Они фиксить проблему собираются?
В 4.4.3.1000 хреново работает качалка. На некоторых файлах доходит до 99% и никак не хочет качать дальше. Вот (для примера) ссылка на проблемный файл https://yadi.sk/d/4vaUmIPlbWHrE