Ericsson, who currently races for Andretti Global, spent five years in F1 earlier in his career and recently commented on Sargeant and his struggles in the category.
"I was also told this weekend by some American friends who know Sargeant, that he doesn't have fun in that team," Ericsson told the Viaplay F1 podcast.
"He thinks it's really hard, and apparently he and James Vowles, they don't even talk with each other anymore. They barely greet each other. It's completely cut off between them."
Sargeant has clearly not taken kindly to Ericsson's comments, hitting back at the 2022 Indy 500 winner ahead of this weekend's Belgian Grand Prix.
"Marcus Ericsson has a reputation of talking about other people without ever even having a conversation with me in his life," Sargeant said when speaking to GPFans and select F1 media.
"So yeah, it doesn't carry any weight. It's not true.
"I just had a conversation with James here 20 minutes ago. And you know, most importantly, me and James, we both come here and we want to do the best for the team, we both work in the same direction for what is the best for the team.
"And ultimately, what's best for the team is best for me. So yeah, it's completely untrue."
Commenting further, Sargeant added that due to how difficult the season has been, his relationship with Vowles may look worse than it is.
"It hasn't been a particularly easy season with the amount of things that have happened both to me, you know, from a team perspective, we've struggled in some areas," the Williams racer continued.
"So, of course, it can look like our relationship is worse than it is from the outside.
"But yeah, we just go to work as usual and keep trying to perform the best we can."