Don't the republicans have full control? Does this mean that there were republicans against the act?

What 'full control' actually means

Full control means one party holds the majority in both chambers and holds the presidency. It does not mean every member of that party votes the same way. Congress is not a monolith. Individual members answer to their own districts, their own donors, and their own political calculations. A majority of one or two seats means a handful of defections can sink or change anything.

The House passed the One Big Beautiful Bill with an extremely thin margin. Several Republican members voted against it, enough that the leadership had to work hard to get it across the line. The reasons varied: some members objected to the Medicaid cuts, some represented districts that would lose out on clean energy tax credits and did not want to give those up, and some had concerns about the overall effect on the federal deficit.

The Senate is a separate vote, and the same dynamic applies there. Full control does not guarantee unity.

Why Republicans break with their own party

A few reasons come up repeatedly in situations like this.

District interests. A Republican representing a rural area that built jobs around wind or solar investment is going to hear from constituents who do not want those credits touched. That pressure is real and local, and it does not disappear because the national party has a different priority.

Deficit concerns. A bloc of Republicans has long argued that the party should be serious about fiscal restraint. A bill that adds trillions to the debt over a decade gives those members a genuine policy objection, not just a tactical one.

Medicaid. Cuts to Medicaid affect hospitals and nursing homes in every state, including deeply red ones. Members from states with large rural hospital networks know what those cuts mean for constituents, and some are unwilling to defend them at home.

The strongest version of each side

The case for the bill is that it extends tax cuts that otherwise expire, reduces regulatory burden, and makes a meaningful attempt to cut federal spending. Supporters argue that economic growth covers more ground than critics project.

The case against is that independent budget analysts score it as adding significantly to the deficit over ten years, the spending cuts fall most heavily on people who depend on Medicaid and food assistance, and the benefits skew toward higher earners and corporations.

Both of those positions have serious people behind them. The question of which trade-off is worth making is yours to weigh.