Advice needed: dmarc setup and mail.ru

I'm not in the security field so sorry if I seem like a newbie. Not sure where else to ask.

I setup my own email domain thing with the help of some kind Lemmy folk. I'm on Namecheap, it was a little tricky for me to set up but it seems to have been working out great.

But yesterday, and again today I got this notice from DMARC that Mail . ru is doing stuff with my account.

advice I was able to google suggest I needed to change a setting from "none" to "reject".

can anyone tell me if I've done this right? also has any damage been done by me not having this set sooner?