Although my restaurant columns have taken on an increasingly taut, Pollyanna-ish “I’m just glad to be out of the house” tone over the past three months, I think Bar des Prés in Mayfair has finally broken me. It was somewhere between the vanilla-flavoured mashed potato and the moment when I realised French celebrity chef Cyril Lignac was not, in fact, cooking in his kitchen during this heavily hyped launch, and was instead jazz-handing about the place in casual clothes and allowing the predominantly French clientele the sumptuous treat of meeting him.

“Non, Cyril,” I thought, “ce n’est pas OK. How about putting on some whites and popping backstage to handle more important matters? Perhaps starting with some sort of judicial inquiry into that purée de pommes de terre à la vanille?” Et voilà! There she was, the old pre-pandemic Fenella The Kettle Witch in me. Not dead, after all, just lying dormant. All it took to reawaken her was an eight-quid side of mash that tasted a bit like Birds Eye arctic roll.

For this, I should probably thank Cyril. Being relentlessly nice and supportive in restaurants, while secretly planning never to darken their doors again, couldn’t last for ever. It certainly isn’t the fault of Bar des Prés that so many restaurants are run poorly and wasting my lipstick right now. The most serious issue is either a dearth of staff or, worse, a plethora of untrained staff let loose on a dining room floor near you, with no natural flair for the magical fairy dance of hospitality. Meanwhile, anyone with even a modicum of interest in making sure glasses are refilled, orders get to the chef, tables wiped and loo rolls replaced in the ladies seems to have been swiftly promoted to manager – and left to sink or swim. Or poached by the one good place left in town, and on far better wages.

As both a customer and critic, I’ve done a lot of smiling graciously in 2021. Because this is all – depending on who you ask – down to Brexit, or the pandemic, or the droves leaving hospitality to rethink their futures, or those others who are re-opening their venues when, if they were honest, they’d rather be at home doing star jumps with Joe Wicks. Or at least a distance-learning reiki healing course, rather than having to make me lunch and endure my cat’s bum tight mouth when they tell me that eight of the 10 items on the menu are unavailable, before leaving a mop bucket in the middle of the aisle for customers to trip over and traipsing off to smoke a fag right outside the window.

None of these things, I hasten to add, happened at Bar des Prés. The service is that attentive, smiley, full-eye-contact type; at times, there were as many as four front-of-house staff around me at once, like a barber’s shop quartet, smiling and telling me how wonderful everything is at Bar des Prés, to the point where I began to wonder if I was being softened up to join Cyril’s cult. No, Bar des Prés is actually a beautifully staffed, well-run joint with so much toilet paper I could have made a nest.

Its main problem is that it is also a lavishly funded, Franco-east Asian restaurant that began life in Paris and is headed up by a chef who has been called the French Jamie Oliver (but who is largely unrecognisable over here). This means that, to the naked eye, it’s just another fancy Mayfair cocktail bar that serves perfectly OK £17 “margarithais” made with tequila, mezcal and lemongrass, and has a menu that’s part-Japanese – obsiblue prawn sushi, yellowtail and otoru sashimi, spicy tuna tataki; and part-French-Asian – langoustine ravioli with yuzu, or artichoke salad with yet more yuzu, this time in a truffle vinaigrette. The sushi and sashimi are made behind the sit-up bar by skilled chefs and are definitely as decent as an £18 plate of seared tuna Californian roll with nori, Korean spices and, ahem, yuzu soy sauce should be.

The few French-ish items on the menu, meanwhile, are many levels of curious. Take “spicy prawn, cos lettuce, sesame seeds”: a bowl of generously dressed, one-note leaves in a sesame oily dressing and a blink-and-you’ll-miss-them garnish of chopped, crisp-coated prawns.

Or the duo of excessively sweet slider-style lobster rolls, or those vanilla potatoes that tasted like when your mum bought you a Mr Whippy and you kept hold of it for a bit too long and it dripped warmly down your hand, or the really rather burnt, but still a signature dish nevertheless, millefeuille with pecan nut praline. That last featured three of the ingredients I adore most in the world, but here it was a plate of punishingly sweet tooth glue.

Yes, I am aware that I am whinging about my not very nice pudding hell. And, yes, I can hear the world’s teeny-tiniest baroque violin playing for me and my distended gullet as I push another dinner into my spoilt cakehole. But I just want to say that, for the first time since the pandemic, I am openly narked about a not-very-good restaurant. I won’t lie: feeling this bad feels quite good.

• Bar des Prés 16 Albemarle Street, London W1, 020-3908 2000. Open all week, noon-11pm (Sun 10pm). From about £60 a head, plus drinks and service.

• Listen to Grace Dent’s new podcast, Comfort Eating, here.