The article doesn't explain how Meta are actually using SPVs. The suggestion is that the debt is in fact Meta's debt but the use of an SPV somehow means they don't need to show it on their balance sheet. Traditionally if you're using an SPV it genuinely means it's not your debt, in that you won't go bankrupt if the deal flops and the assets are underwater. (And they're not your assets, either.)
There are valid concerns about debt fuelling outsized investments in AI, but this article isn't really saying anything of substance. Plenty of non-bubbles attract significant debt investment as well.
Ultimately, debt is a way to transfer risk. It becomes an issue if it results in a lot of risk being transferred to parts of the economy that can't really afford it (like retail investors, or systemically important banks). As long as the people taking on the risk know what they're getting into and we won't need to bail them out if they lose their shirt, it's not really a problem.