Sometimes, formality is necessary, and "thank you" is still the best choice in such situations.

有时候，正式是必要的，在这种情况下，“谢谢”仍然是最好的选择。

youdao

We each need to find the right level of formality that's necessary for the project and team that we are working with.

我们每个人都需要找到合适等级的程序，那对于我们所工作的项目和团队都是必要的。

youdao

Staff have had to be offered voluntary redundancy, but chief executive Mike Lazenby said this was a formality necessary under business law and he hoped nobody would want to take redundancy.

BBC: NEWS | UK | England | Kent | Company in high street 'transfer'