Yes, but it's just not statistically significant. Unless we see longer-term trends of her follow count, this could easily be a random fluctuation, bot crackdown, etc.
Bots are routinely rounded up and banned. A lost follower is not necessarily an unfollow.
The article is reaching for a narrative. The lady they talk about has done other things in this period of time. Other stuff has happened. The change in followers is minuscule in relation to the magnitude, so it could be noise.
It could be homophobia obviously. It could be some controversy about unfortunate body image declarations. It could be noise. It could be the war on Middle East and a round of banned bots. It could be too much time since the last record. She could be losing the spotlight. The social network could be purging deleted accounts.
The reason “homophobia” is a guess. The reason “bots” is another. None invalidates the other because in both cases you have to make assumptions about the motives of 100.000 entities.
Also could be 5.100.000 followers lost and 5mil gained. The article talks about the delta, but there is not a reliable analysis about the composition of the following and its change over the last months, except one simple number.
However, I can't say I listen to or follow Billie Eilish - I only found out about her coming out from reading this, in fact - but even as someone who's just mildly aware of her, I will say I've never assumed her to be straight. My gaydar's probably better tuned than the average person's but even so, I feel like her being some flavour of queer was fairly obvious and I wouldn't be at all surprised if that's influenced / shaped the kind of audience she has.
Unfortunately, I suspect an artist who's less obviously queer would lose a larger following for coming out. But yes, Billie Eilish only losing 100K followers is really encouraging still!