How did the Loki Variants know Alioth's name?

Is Alioth's name really Alioth?

I'll argue that we only ever see the Loki variants call Alioth, Alioth. The only time other than that we see it being called Alioth is by He Who Remains and he only ever does so once Loki calls it Alioth. It's possible that he's just using the name that they call it for ease.

He Who Remains: That first variant encountered a creature created from all the tears in reality, capable of consuming time and space itself. A creature... you both know.

Loki: Alioth.

He Who Remains: Bingo! I harnessed the beast's power and began experimenting on it. I weaponized Alioth and I ended... I ended the Multiversal War.

_{Loki, Season 1 Episode 6, "For All Time, Always"}

Note that He Who Remains knows all and has seen all so he'll be very aware of what name they use for Alioth. In fact he already knows that Loki is going to call it Alioth. Once again he could just be using the name that they're familiar with.

He Who Remains: But how do I already have it loaded up with everything I need to know to keep from being killed by you two? It's easy. I know it all. And I've seen it all.

_{Loki, Season 1 Episode 6, "For All Time, Always"}

Enchanted?

Alioth might not be able to talk, that we've seen, but that doesn't mean they can't find out his name, or a name, for him by reading its mind. All the Loki variants have access to the same power(s) but they all but their strengths in different ones. We actually saw Loki Prime in Thor: Ragnarok read Valkyrie's mind, for instance. It's possible that one of the current Loki variants, or a previous one, attempted the same plan and failed but managed to connect enough to learn information about Alioth, such as his name.

Time Loop?

There's a theory that the whole MCU universe/multiverse is in a time loop. That a Multiversal War takes place which is eventually resolved by He Who Remains who puts the timeline into balance as the Sacred Timeline. After eons Loki and Sylvie turn up and kill He Who Remains unleashing the multiverse and setting another Multiversal War on the go. And so it repeats.

There's a few things that He Who Remains says that pave way for this theory but one clear one is "I'll see you soon" just before Sylvie kills him. At face value this could refer to other variants of himself, however, it could also refer to himself when he once again sets out to end the Multiversal War.

What this means is that the Lokis who exist and survive in the Void can keep surviving there passing information along. Maybe Sylvie comes back to them and confirms Alioth's name or something else completely for how they learn the name. Note that the Void and the Citadel at the End of Time exist outside of time and so should be unaffected by changes to it.

This one's a bit more speculative and hand-wavey of course but I thought I'd add it to be complete.