One onlooker even went as far as to allege that the group were drinking alcohol, which can reportedly cost up to £1,500 (approximately $2,600) a bottle at the venue.
“Bea should be setting a better example. I couldn’t believe my eyes. If the Royal Family can’t get coronavirus rules right, what hope for the rest of us?” one onlooker claimed.
According to the currently enforced Tier 2 rules in the UK, social gatherings from different households are banned indoors and must be held outside instead - unless the gathering is business-related.
The shocked diner went on to say the group appeared to be having a good time, but Beatrice’s seemingly nonchalant approach to COVID restrictions was not appropriate.
"There is a very serious side to this and Beatrice deserves a ticking off,” the diner said, referring to an up-close photo Bea took with fashion designer Peter Dundas.
In the candid photo, the princess poses shoulder to shoulder with Peter, who later shared the snap on his Instagram account.
“Urban Jungle catching up w this lovely #BeaYork #Dundasgirl #NewMasks #TigerMask #CammoMask #AnimalEdit,” Peter captioned, referring to their donned masks.
The onlooker added: “We’re going backwards in London in the fight against coronavirus and high-profile people behaving with such a cavalier attitude to the pandemic are part of the problem.”
The backlash comes after Bea was labelled a “f****** idiot”, after she allegedly failed to acknowledge she cut British singer Ed Sheeran’s face, during a party prank that went horribly wrong.
The 32-year-old reportedly sliced the singer’s face while pretending to “knight” fellow musician James Blunt at a party at Royal Lodge in Windsor in 2016.
Speaking about the incident to The Telegraph, Ed’s manager Stuart Camp said he was disappointed Beatrice hadn't reached out following the party.
“I got quite protective over that,” Stuart told the British publication. “Because we’ve never publicly commented on it.”
He went on to claim that he made the decision to not “out” Beatrice, despite several people allegedly telling him to say that it was someone else.
“I’m not lying, just because someone’s a f****** idiot. Because they’re thinking, ‘yeah, I will get paralytic and take a sword off the wall.' You’re just asking for trouble,” he added.