How do I convince my data engineer to not modify data before including it in our db?

Our data engineer insists in lowercasing everything and removing some other formatting like new lines on free text fields.

They say it's "better for elastic search".

To me that makes no sense and loses information that can't be added back. But I couldn't really convince them otherwise. So far no real problem has come out of it but it makes for a worse experience for the user. Like company names that are acronyms show up as all lowercase. (ibm, llc, etc.) or free text fields that we miss when the user wrote in caps or added paragraphs.

What are your thoughts on this?

Disclaimer, I'm not a data engineer. Just a PM from a data related product.