The 22-year-old Belgian midfielder spoke to the Daily Mail ahead of Saturday's FA Cup final against Manchester City, offering the most candid account yet from inside Chelsea's dressing room of the night that ended Liam Rosenior's tenure as head coach.
Rosenior called the performance "indefensible" and "unprofessional" at full time and was sacked the following day, with the fifth successive league defeat without scoring proving the breaking point for the club's hierarchy.
"We've always said things that the other person needed to hear. I'd probably say Brighton was a special one because we knew how important it was. It just felt like everything was going against us."
Lavia described an honest dressing room conversation following the defeat.
"We had a good conversation. We made sure that, even if we didn't get the result in the following game, we couldn't give the chance to anyone to say that we've 'given up' — because that's not the case, even if it might have felt like that against Brighton."
That next game was the FA Cup semi-final at Wembley, which Chelsea won 1-0 against Leeds United under new interim manager Calum McFarlane.
On the broader accusation that the squad orchestrated the result to force Rosenior out.
"It is tough to hear because you know the work that you put in every single day. We are at Chelsea so every time something doesn't go our way, we're going to get criticised. It's something we are conscious of. The most important is to not pay attention to it, and if you do, try using it in the right way as motivation to turn it around. To say we don't listen to it would be a lie. But we use it in a good way."
On whether winning the FA Cup would rescue the season.
"Would that make it a good season? You can argue that all day. We want to win every competition we are in, so obviously we are disappointed. We have to make the most of what's left. We all have to take part of the responsibility. Sometimes it is easy because you see the manager leaving and a new one coming in. But as players we need to show that we don't just point at one person. If things happen, we are also a part of it because we are the ones on the pitch. We definitely take it to heart."
Lavia joined Chelsea from Southampton for £58 million in the summer of 2023 and has spent much of the two and a half years since in and out of the treatment room. He has been one of the more consistent performers when fit this season.