Of all the songs her fans would want Lady Gaga to play twice in one night, it seems unlikely that many would choose Scheiße. Quite literally called Shit, this camp, Euro-club bagatelle off the singer’s Born This Way album of 2011 is sung-spoken in made-up comedy German.

Tonight, on the first show of the UK leg of Gaga’s rescheduled European tour, after a heartfelt preamble about overcoming obstacles and “being strong without somebody else there”, after a load of fierce choreography on a vertiginously tilting tripartite stage, Lady Gaga announces that there has been a technical error – one entirely unnoticed by the sell-out crowd.

The gig is being filmed, and Gaga wants to do the song again. The show has just hit its exultant stride. And now, suddenly, the fourth wall separating performance from reality drops away. Rather than feeling like a deliciously unscripted moment, it’s as if we have all become mere extras in a giant film set.

The thought occurs that this first of two Birmingham gigs, in two different venues due to popular demand, is actually serving some future Joanne tour DVD rather than prioritising the moment.

It’s a dislocation that dogs this marathon gig through peaks, longueurs, costume changes, 22 songs and one spectacular, lump-in-the-throat moment near the end that you fervently hope is unscripted.

Artifice, and a level of meta-performance, have long been at the heart of Lady Gaga’s seductive, 21st-century pop offering – until very lately. Early singles such as Paparazzi – both ballsy and wistful tonight – willed the feral packs of photographers into her orbit.

Calling her 2008 debut album The Fame engineered the very stardom Gaga craved, in order for her to be blasé about it. For most of her imperial tenure through the past decade, she has appeared in public less as a celebrity of flesh and blood and more as a preening art installation, once dressing as an actual star, once, infamously, decked out in bloody flesh.

It is axiomatic that pop stars will reinvent themselves, particularly when an album like 2013’s high-concept Artpop failed to connect as Gaga’s previous albums had. With this fifth album, Joanne (2016), Gaga stripped back the layers, both visually and aurally, offering up a less processed iteration of the now 31-year-old singer, a trajectory towards the “real” that included last autumn’s riveting Netflix documentary, Five Foot Two.

As Gaga tells it on stage tonight, in one of many spoken segments, producer Mark Ronson asked the singer what theme she would choose for an album if she could only make one more, and she replied: “Joanne”. Joanne was Gaga’s aunt who died in 1974, aged 19, of the autoimmune disease lupus, a loss that scarred the Germanotta family indelibly, Gaga’s father in particular. Five Foot Two bore witness to the making of Joanne-the-album, and Gaga’s own struggle with injury and chronic fibromyalgic pain (the reason this tour was rescheduled). Joanne had fewer concepts, and more guitars and piano ballads; Gaga wore cut-off denim shorts rather than the pelts of discarded Kermit the Frogs. A load of rumoured new songs with RedOne – the producer of many of her most memorable hits – were left off the record.

The album’s occasional Broadway bent and strange conventionality does not translate seamlessly to this busy arena tour, which tries to reconcile all Gagas, past and present. The stop/start pacing is problematic – especially when the crowd are made abruptly aware that there is a bigger picture (the filming) beyond the sacred rush of the moment.

The “real” proves a mixed bag for Stefani Germanotta. On the one hand, on Joanne songs such as Million Reasons, played out on a distant B stage reached by a system of bridges over lilypad sub-stages, the singer re-emphasises her vocal range and musical chops, something that her Autotuned early records glossed over.

On the other, all the heartfelt hollering at the transparent laser-lit piano renders Gaga almost ordinary tonight, on a level with any number of common-or-garden female belters. You miss US pop’s imperious, otherworldly maven, the one with the banging, futurist anthems (Bad Romance remains one of the greatest pop songs ever written by anybody) and razor-sharp cheek prosthetics.

The best thing about manufactured pop at this giddy-high level is its highly synthetic, ridiculous, quasi-monstrous nature. When Gaga appears, wrangling a keytar in a rhinestone get-up with huge shoulder pads for Just Dance, her very first hit, the feeling is one of glorious relief, as that fourth wall goes back up and some semblance of the old outré weirdness is restored.

While the windswept Born This Way and Edge of Glory are still two of Gaga’s greatest hits, other rockier songs – such as A-Yo, which features four guitarists, including Gaga – seem to perform “rock”, with bombastic solos and gurning. Lengthy guitar workout codas fill the gaps from song to video interlude.

If the codas are long, the set’s visual padding – the videos that play during the costume changes – actually provide the most visually creative parts of the show. In one segment, Gaga spins around in a vintage GTO car that spits pink smoke. In another, she transforms from a tipsy showgirl into a long-taloned creature from a horror film, echoing her Edward Scissorhands Halloween costume. In a third, she sports double rhino horns.

The “real” has its occasional appeal though. Gaga does a lot of good talking – about loneliness and feeling different, about LGBTQ equality, about enduring pain, and how we can fix hurt with love. All of it feels meaningful, even if she said the same thing in Amsterdam the other night.

Nothing illustrates those core Gaga themes better than a letter, balled up and thrown onstage after Bad Romance. “A monstergram!” Gaga announces, retrieving it. It’s from a teenager called Conor who has travelled from Belfast with his brother for the gig. All pop stars have rabid fanbases, but the resonance between Gaga and her “little monsters” has always been particularly potent.

A superfan since a tender age, Conor tells in his letter how Gaga’s music and message of fabulousness has made him feel less lonely at his secondary school. The cameras cut to a stunned-looking young man in the front row clutching at his face, from which all the blood has drained. “Although I doubt you’ll ever see this letter,” Gaga reads out at one point. The whole arena chokes up as one.