Absolutely! I remember reading this paper [0] about personalized pricing. The fact that personal data (an IP) is being used to inform prices has to be disclosed in the GDPR disclosure of a website. A very simple way to avoid a lot of those issues however is to have time-limited experiments in which 100% of Country's flow is directed towards one experiment (in the case of Corrily we keep track of which user saw what price when to insure the user will always see the same price).

[0] https://www.econstor.eu/bitstream/10419/205221/1/de-Streel-J...