Advice on a disconnected team member

I’d seeking advice on how to raise with a highly introverted employee my concern about their disconnection from the rest of the team. It’s driving a lack of empathy for their co-workers that is causing some tension and offence from others, and miscommunication when they don’t really understand what others are contributing or have on their plate. This person will often comment that ‘they are the only one doing any work’ when others are doing a huge amount of work - it just is not visible to them because they don’t participate in team activities or have much interest outside their sphere of responsibility. We have a very sociable and engaged team, but operate remotely and hybrid. I notice that this team member very often does not participate in group activities online or in person, and chooses to stay away from the office more often than not. They also seem to not notice or participate in the team habits of thanking one another or acknowledging each other online when we are all remote. They are a fantastic worker, but are unintentionally causing offence. How do I raise sensitively and encourage them to be part of the team norms and culture.