Hayley Williams featured on the American Football song "Uncomfortably Numb" in 2019[5] and released two solo albums, Petals for Armor (2020)[6] and Flowers for Vases / Descansos (2021);[7] the former produced by Paramore guitarist Taylor York.

[9] Farro continued his ongoing project HalfNoise, releasing an extended play – Flowerss (2018) – and two albums – Natural Disguise (2019) and Motif (2021).

[10] Farro also recorded drums for the songs "Watch Me While I Bloom" and "Crystal Clear" from Williams' Petals for Armor[11] and released an EP under his own name titled Zafari (2020).

Williams hinted that the band's next album would be more guitar-driven, stating, "We've found ourselves listening to a lot of older music that we grew up being inspired by.

Logan Gourlay of Rock Sound called it a "jittery post-punk record" and noted Foals, Bloc Party and Talking Heads influences.

"[21] Ims Taylor of Clash stated that "Paramore opt for simple, striking, and forceful on ‘This Is Why’, keeping in that New Wave tradition of punchy phrases iterated and reiterated, through vivid guitar countermelodies, offbeat punctuation and pointed lyrical looping of lyrics that go beyond verse chorus verse chorus, searing each song's character into your mind indelibly.

"[23] According to Chris Thiessen of Under the Radar, "The back half of the album feels tonally different from the front, more personal and relational and coming closer to their pop-punk roots.

"[24] Maximo David of Boolin Tunes states "any notion that This Is Why is Paramore 'returning to their roots,' or whatever a number of pundits may have purported over the years is almost unequivocally false.

"[22] Sarah Jamieson of DIY called the album "another bold and brilliant transformation for the trio" with a "real sense of self-assuredness" that is "Paramore's most ambitious record yet".

[48] Writing for Evening Standard, David Smyth felt that the album "ranges from volcanic energy to slower tracks that suggest an appealing maturity.

"[20] Alexis Petridis of The Guardian wrote that on the album, "the agitated drumming and angular guitars meld with the big riffs and stop-start dynamics of pop-punk and an acute understanding of pop songcraft", concluding that it "tackles millennial malaise really well and realistically".

[45] According to Steven Loftin writing for The Line of Best Fit, "Like all good jangling indie bops, beneath the fluctuations of chipper notes swims a dark underbelly, and This Is Why relishes in this fact.

"[46] Reviewing the album for NME, Sophie Williams found it to be "as in tune with the textures of today's forward-thinking rock as much as it is a love letter to Paramore's brilliantly caustic early days", with "some of their most fearless songwriting to date" and the band having "uncovered a new warmth".

"[24] In June 2023, Alternative Press published an unranked list of the top 25 albums of the year to date and included this release, calling it "anything but reserved" as the band "boldly and artfully dig into politics, discomfort, and mental health while finding a funkier, more complex musical canvas with which to explore and express themselves freely".