olefy_macro Spam rating, but there is no macro in the file

Hi there,
I’m running a mailcow (up to date) with pretty standard configuration.
I’m trying to send a csv file to my mailbox an said mailcow. The mails get directly bounced.
Looking at the rspamd logs it says “OLEFY_MACRO (20)”. But it is a plain text file, there are no macros.
By further investigation I found out, that this happens completely independent of file content.
.csv files smaller then 500 bytes get accepted, 500 bytes and larger get flagged by olefy_macro, even 500 bytes of just zeroes. The same file of 500 bytes of zeroes with .txt ending gets accepted.
I’ll attach the test file an the relevant logs, hope someone can help.

Edit: ironically my upload of the 500 bytes of zeroes .csv file gets changed to .txt by the forum.