Yeah, he's misread that, though it's perhaps understandable.
This is an understandable confusion. As luciagen says, I'm saying something like this: "they haven't even given vague mentions in their update logs, which is their usual practice", where the "which" is a relative pronoun ("as" can serve a related function, maybe less known to a non-native speaker) pointing to "giving vague mentions in update logs". You've read the pronoun as pointing to the whole phrase including the negation "not", but that's not what I'm saying. Their usual practice is, indeed, to give very vague update log entries "general stability and gameplay improvements", etc. It's always been infuriatingly vague, but it's common enough to be their practice.
I know you never claimed that it was; it's old ground at this point.
Specifically re the claim that Thursday server maintenance updates sometimes also included gameplay elements, as claimed by others, I think it's always been a very fanciful and cognitively biased evidence base. People claim they see a new animation – I sometimes see a "new" animation in PES 2021 having played the game essentially for 3 years now. Sometimes we forget or fail to notice things we've already seen; sometimes the triggering scenarios for an animation can be quite rare for the playing scenarios of a given player.
As for the present claims of people that eFootball has been secretly updated: I do think the burden of proof lies with them, as it generally does when you want to make an existential claim in the face of a shared experience where plenty of people see no changes. If you tell me there's actually an elephant behind the door, I've just not seen it yet, and when I look it's not there, and there's no elephant dung or mess created by it, I have to return to you and ask for some evidence if you're to be taken seriously. My claim in the face of no elephant evidence at that point, to the effect that it's not there and you've probably imagined it, presents a less heavy evidential burden on me than it does on you.
In any case, we both agree the game hasn't been secretly updated, or at the least that it's very unlikely. Happy to leave it there.