TIPS bonds are inflation protected. Although they're not ineffective at any point in time, I would argue during lower periods of inflation they are less effective.. The time to own TIPS would have been when inflation was sky-high in 2022.
I would argue that something like UBIL would be the more effective way to get exposure to treasuries at this point in time. It isn't inflation protected but it is also higher yielding because of this. The difficulty there is UBIL trades in USD.
The primary reason one would hold TIPS bonds is if you believe inflation is going to ramp back up again. In this situation, these bonds would be extremely effective. I imagine they are getting a lot of chatter right now with Trump's policies potentially fueling inflation.
Predicting these economic situations is nearly impossible. Even the best economists in the world can't do it with any sort of accuracy so I don't really try to do it myself.
Ultimately, high inflation is good for TIPS. If you believe we are going to go back to something like that, they are highly effective. Otherwise, normal treasuries will give you higher risk-free yields.