Out of the loop

Strictly speaking, it's not unbanned. Rather, the deadline by which this will happen keeps getting extended.

The first extension occurred back in January as reported in https://www.forbes.com/sites/esatdedezade/2025/01/20/tiktok-was-unbanned-after-just-12-hours-heres-why/ (and actually the app was down for about 12 hours before getting restored).

The second extension was reported here https://www.bbc.com/news/articles/cx256dd1znpo which provides the "official" rationale - the President wants TikTok to be sold and is trying to give more time to get that deal concluded. In fact it seems the deal was almost concluded but got yanked at the last moment due to the tariff actions.

As to why the President is so willing to grant extensions to get a deal done (as opposed to, say, letting the ban take effect and only allowing restoration once the app has actually been sold), https://www.statesman.com/story/news/state/2025/01/22/tiktok-ban-banned-trump-who-bought-2025-meta-elon-musk-ceo-reversal-executive-order-delay/77852924007/ has some good thoughts why.

Two important points - a younger generation likes TikTok, who he may now be loathe to alienate, and also that it was Biden who signed the ban into law - so by getting TikTok sold and unbanned, it's another reversal of something that Biden did.

If a deal to sell TikTok fails to happen by June, it's still possible that the ban will go into effect then. Though, if you were going to bet that a third extension would be granted, I wouldn't be willing to take the other side of that bet.