The senior dev is toxic. Any member should feel easy to ask any questions, no matter how experienced they are. It's almost always better to ask questions immediately.
I've also made mistakes by not asking questions.
I joined a team as a senior dev and worked there for more than ten months. Sometimes, I felt like I didn't understand very basic contexts in the meetings. I couldn't ask what they were talking about because I was afraid of being seen as an incompetent dev.
It turned out that they forgot to invite me to one of the most important Slack channels, where the product owner, the marketing team, the executives, and devs had discussions on important business decisions and the direction of the entire dev team. I was the only member who didn't follow the channel, so know nothing about the important decisions.
We found out that after ten months, and they apologized for the mistake. And they even prized me for being productive despite not knowing the decisions made in the channel. But I was really ashamed of myself. I felt like I lacked some basic context a dozen times but never asked "sorry, what are you talking" even a single time. Instead, I pretended to understand what they said.
Once I followed the discussions there, I became more productive due to much fewer communication errors on the business decisions and direction of the dev team. Since then, I've tried to ask any questions as soon as possible.