The English duo were filmed at a restaurant in Mayfair in London.
Both of them were at the crowded location, along with other partygoers.
It appears their actions are a breach of the Tier 2 rule for the area, per The Sun.
The rule states "you must not socialise with anyone you do not live with or who is not in your support bubble in any indoor setting, whether at home or in a public place."
Barkley was celebrating his 27th birthday, and Grealish was in attendance.