The full warning message I get in the
Package biblatex Warning: Conflicting options.
(biblatex) '<namepart>inits' conflicts with 'uniquename=full'.
(biblatex) Setting 'uniquename=init' on input line 10.
This tells you that since you only want given/first name initials with the option
giveninits, you can't get full uniquename disambiguation if need be (as automatically requested by the
authoryear style with
uniquename=full). The message goes on to say that the option will be set to
to allow for name disambiguation at least by name initials.
If you don't want the warning in the first place, just load
uniquename=init from the start.
If you don't want name disambiguation at all, use
uniquename=false instead (see biblatex, authoryear style: In-text citations display first name initials for certain bibliography entries for example).