Six Republicans voted present when Schiff was censured. Five of these Republicans are members on the Ethics committee.

Here are the names of the 6 Republicans in second paragraph:

https://www.foxnews.com/politics/adam-schiff-censured-6-republican-lawmakers-break-party-vote-present

If you read any article about Schiff's censure, you would see that Schiff is also going to be investigated by the Ethics committee.

Look here in the second paragraph:

https://rollcall.com/2023/06/21/revised-schiff-censure-advances-impeachment-votes-could-be-next/

Now, look here at the names on the Ethics committee for the Majority.

https://en.wikipedia.org/wiki/United_States_House_Committee_on_Ethics

I think it would look like a conflict of interest if the members of the Ethics committee voted to censure Schiff and then later investigated him. They would look as though they already found Schiff guilty of crimes before the investigation began. By voting "Present" they kept any bias out of future investigations.