Well, the C5 doesn’t typically last the whole lap in Bahrain so I can see why many teams chose not to bring it.

Are the tires the same as last year, or have Parelli tweaked them?

I haven’t read anything about it, but we’re back to 5 tyres so something has changed. Last year we had the C0 too, remember. Most likely they just removed that and went on with their day, if I remember right it was awful last year too (last years’ C0 was the infamous 2022 C1).