I may be misremembering but I don’t think the last bit of chapter 5 was there before. The uploader might just be adding the remaining parts of chapter 5 as they re-upload it since the official English version of this manga is uploaded in sections on the site rather than in its entirety. :)
The last part wasn’t there before
I assume you havent read the last tn notice. This manga is uploaded weekly but not with full chapter, it is divided to several parts. Consensus decided that it is better to get it as fast as possible (weekly) with only few pages, rather than wait for a month for full chapter. That's why you might see they uploaded one chapter several times
Where can I find the official release?
They reap loaded this same chapter 3 times now